diff --git a/lib/downloader.js b/lib/downloader.js
index 0c56cc3..25dcc0a 100644
--- a/lib/downloader.js
+++ b/lib/downloader.js
@@ -3,6 +3,7 @@
  * 详细设计文档可查看 https://juejin.im/post/5b42d3ede51d4519277b6ce3
  */
 const util = require('./util');
+const hash = require('./hash');
 
 const SAVED_FILES_KEY = 'savedFiles';
 const KEY_TOTAL_SIZE = 'totalSize';
@@ -40,25 +41,34 @@ export default class Dowloader {
         resolve(url);
         return;
       }
+      const fileName = getFileName(url);
       if (!lru) {
         // 无 lru 情况下直接判断 临时文件是否存在，不存在重新下载
         wx.getFileInfo({
-          filePath: url,
+          filePath: fileName,
           success: () => {
             resolve(url);
           },
           fail: () => {
-            downloadFile(url, lru).then((path) => {
-              resolve(path);
-            }, () => {
-              reject();
-            });
+            if (util.isOnlineUrl(url)) {
+              downloadFile(url, lru).then(path => {
+                resolve(path);
+              }, () => {
+                reject();
+              });
+            } else if (util.isDataUrl(url)) {
+              transformBase64File(url, lru).then(path => {
+                resolve(path);
+              }, () => {
+                reject();
+              });
+            }
           },
         })
         return
       }
 
-      const file = getFile(url);
+      const file = getFile(fileName);
 
       if (file) {
         // 检查文件是否正常，不正常需要重新下载
@@ -77,16 +87,70 @@ export default class Dowloader {
           },
         });
       } else {
-        downloadFile(url, lru).then((path) => {
-          resolve(path);
-        }, () => {
-          reject();
-        });
+        if (util.isOnlineUrl(url)) {
+          downloadFile(url, lru).then(path => {
+            resolve(path);
+          }, () => {
+            reject();
+          });
+        } else if (util.isDataUrl(url)) {
+          transformBase64File(url, lru).then(path => {
+            resolve(path);
+          }, () => {
+            reject();
+          });
+        }
       }
     });
   }
 }
 
+function getFileName(url) {
+  if (util.isDataUrl(url)) { 
+    const [, format, bodyData] = /data:image\/(\w+);base64,(.*)/.exec(base64data) || [];
+    const fileName = `${hash.sha256(bodyData)}.${format}`;
+    return fileName;
+  } else {
+    return url;
+  }
+}
+
+function transformBase64File(base64data, lru) {
+  return new Promise((resolve, reject) => {
+    const [, format, bodyData] = /data:image\/(\w+);base64,(.*)/.exec(base64data) || [];
+    if (!format) {
+      console.error('base parse failed');
+      reject()
+    }
+    const fileName = `${hash.sha256(bodyData)}.${format}`;
+    const path = `${wx.env.USER_DATA_PATH}/${fileName}`;
+    const buffer = wx.base64ToArrayBuffer(bodyData.replace(/[\r\n]/g, ""));
+    const result = wx.getFileSystemManager().writeFileSync(path, buffer, 'binary');
+    if (!result) {
+      wx.getFileInfo({
+        filePath: path,
+        success: (tmpRes) => {
+          const newFileSize = tmpRes.size;
+          lru ? doLru(newFileSize).then(() => {
+            saveFile(fileName, newFileSize, path).then((filePath) => {
+              resolve(filePath);
+            });
+          }, () => {
+            resolve(path);
+          }) : resolve(path);
+        },
+        fail: (error) => {
+        // 文件大小信息获取失败，则此文件也不要进行存储
+          console.error(`getFileInfo ${path} failed, ${JSON.stringify(error)}`);
+          resolve(path);
+        },
+      });
+    } else {
+      reject()
+    }
+  });  
+}
+
 function downloadFile(url, lru) {
   return new Promise((resolve, reject) => {
     wx.downloadFile({
diff --git a/lib/hash.js b/lib/hash.js
new file mode 100644
index 0000000..d42fd30
--- /dev/null
+++ b/lib/hash.js
@@ -0,0 +1,255 @@
+/* SHA256 logical functions */
+function rotateRight(n, x) {
+  return (x >>> n) | (x << (32 - n));
+}
+function choice(x, y, z) {
+  return (x & y) ^ (~x & z);
+}
+function majority(x, y, z) {
+  return (x & y) ^ (x & z) ^ (y & z);
+}
+function sha256_Sigma0(x) {
+  return rotateRight(2, x) ^ rotateRight(13, x) ^ rotateRight(22, x);
+}
+function sha256_Sigma1(x) {
+  return rotateRight(6, x) ^ rotateRight(11, x) ^ rotateRight(25, x);
+}
+function sha256_sigma0(x) {
+  return rotateRight(7, x) ^ rotateRight(18, x) ^ (x >>> 3);
+}
+function sha256_sigma1(x) {
+  return rotateRight(17, x) ^ rotateRight(19, x) ^ (x >>> 10);
+}
+function sha256_expand(W, j) {
+  return (W[j & 0x0f] +=
+    sha256_sigma1(W[(j + 14) & 0x0f]) +
+    W[(j + 9) & 0x0f] +
+    sha256_sigma0(W[(j + 1) & 0x0f]));
+}
+
+/* Hash constant words K: */
+var K256 = new Array(
+  0x428a2f98,
+  0x71374491,
+  0xb5c0fbcf,
+  0xe9b5dba5,
+  0x3956c25b,
+  0x59f111f1,
+  0x923f82a4,
+  0xab1c5ed5,
+  0xd807aa98,
+  0x12835b01,
+  0x243185be,
+  0x550c7dc3,
+  0x72be5d74,
+  0x80deb1fe,
+  0x9bdc06a7,
+  0xc19bf174,
+  0xe49b69c1,
+  0xefbe4786,
+  0x0fc19dc6,
+  0x240ca1cc,
+  0x2de92c6f,
+  0x4a7484aa,
+  0x5cb0a9dc,
+  0x76f988da,
+  0x983e5152,
+  0xa831c66d,
+  0xb00327c8,
+  0xbf597fc7,
+  0xc6e00bf3,
+  0xd5a79147,
+  0x06ca6351,
+  0x14292967,
+  0x27b70a85,
+  0x2e1b2138,
+  0x4d2c6dfc,
+  0x53380d13,
+  0x650a7354,
+  0x766a0abb,
+  0x81c2c92e,
+  0x92722c85,
+  0xa2bfe8a1,
+  0xa81a664b,
+  0xc24b8b70,
+  0xc76c51a3,
+  0xd192e819,
+  0xd6990624,
+  0xf40e3585,
+  0x106aa070,
+  0x19a4c116,
+  0x1e376c08,
+  0x2748774c,
+  0x34b0bcb5,
+  0x391c0cb3,
+  0x4ed8aa4a,
+  0x5b9cca4f,
+  0x682e6ff3,
+  0x748f82ee,
+  0x78a5636f,
+  0x84c87814,
+  0x8cc70208,
+  0x90befffa,
+  0xa4506ceb,
+  0xbef9a3f7,
+  0xc67178f2
+);
+
+/* global arrays */
+var ihash, count, buffer;
+var sha256_hex_digits = "0123456789abcdef";
+
+/* Add 32-bit integers with 16-bit operations (bug in some JS-interpreters: 
+overflow) */
+function safe_add(x, y) {
+  var lsw = (x & 0xffff) + (y & 0xffff);
+  var msw = (x >> 16) + (y >> 16) + (lsw >> 16);
+  return (msw << 16) | (lsw & 0xffff);
+}
+
+/* Initialise the SHA256 computation */
+function sha256_init() {
+  ihash = new Array(8);
+  count = new Array(2);
+  buffer = new Array(64);
+  count[0] = count[1] = 0;
+  ihash[0] = 0x6a09e667;
+  ihash[1] = 0xbb67ae85;
+  ihash[2] = 0x3c6ef372;
+  ihash[3] = 0xa54ff53a;
+  ihash[4] = 0x510e527f;
+  ihash[5] = 0x9b05688c;
+  ihash[6] = 0x1f83d9ab;
+  ihash[7] = 0x5be0cd19;
+}
+
+/* Transform a 512-bit message block */
+function sha256_transform() {
+  var a, b, c, d, e, f, g, h, T1, T2;
+  var W = new Array(16);
+
+  /* Initialize registers with the previous intermediate value */
+  a = ihash[0];
+  b = ihash[1];
+  c = ihash[2];
+  d = ihash[3];
+  e = ihash[4];
+  f = ihash[5];
+  g = ihash[6];
+  h = ihash[7];
+
+  /* make 32-bit words */
+  for (var i = 0; i < 16; i++)
+    W[i] =
+      buffer[(i << 2) + 3] |
+      (buffer[(i << 2) + 2] << 8) |
+      (buffer[(i << 2) + 1] << 16) |
+      (buffer[i << 2] << 24);
+
+  for (var j = 0; j < 64; j++) {
+    T1 = h + sha256_Sigma1(e) + choice(e, f, g) + K256[j];
+    if (j < 16) T1 += W[j];
+    else T1 += sha256_expand(W, j);
+    T2 = sha256_Sigma0(a) + majority(a, b, c);
+    h = g;
+    g = f;
+    f = e;
+    e = safe_add(d, T1);
+    d = c;
+    c = b;
+    b = a;
+    a = safe_add(T1, T2);
+  }
+
+  /* Compute the current intermediate hash value */
+  ihash[0] += a;
+  ihash[1] += b;
+  ihash[2] += c;
+  ihash[3] += d;
+  ihash[4] += e;
+  ihash[5] += f;
+  ihash[6] += g;
+  ihash[7] += h;
+}
+
+/* Read the next chunk of data and update the SHA256 computation */
+function sha256_update(data, inputLen) {
+  var i,
+    index,
+    curpos = 0;
+  /* Compute number of bytes mod 64 */
+  index = (count[0] >> 3) & 0x3f;
+  var remainder = inputLen & 0x3f;
+
+  /* Update number of bits */
+  if ((count[0] += inputLen << 3) < inputLen << 3) count[1]++;
+  count[1] += inputLen >> 29;
+
+  /* Transform as many times as possible */
+  for (i = 0; i + 63 < inputLen; i += 64) {
+    for (var j = index; j < 64; j++) buffer[j] = data.charCodeAt(curpos++);
+    sha256_transform();
+    index = 0;
+  }
+
+  /* Buffer remaining input */
+  for (var j = 0; j < remainder; j++) buffer[j] = data.charCodeAt(curpos++);
+}
+
+/* Finish the computation by operations such as padding */
+function sha256_final() {
+  var index = (count[0] >> 3) & 0x3f;
+  buffer[index++] = 0x80;
+  if (index <= 56) {
+    for (var i = index; i < 56; i++) buffer[i] = 0;
+  } else {
+    for (var i = index; i < 64; i++) buffer[i] = 0;
+    sha256_transform();
+    for (var i = 0; i < 56; i++) buffer[i] = 0;
+  }
+  buffer[56] = (count[1] >>> 24) & 0xff;
+  buffer[57] = (count[1] >>> 16) & 0xff;
+  buffer[58] = (count[1] >>> 8) & 0xff;
+  buffer[59] = count[1] & 0xff;
+  buffer[60] = (count[0] >>> 24) & 0xff;
+  buffer[61] = (count[0] >>> 16) & 0xff;
+  buffer[62] = (count[0] >>> 8) & 0xff;
+  buffer[63] = count[0] & 0xff;
+  sha256_transform();
+}
+
+/* Split the internal hash values into an array of bytes */
+function sha256_encode_bytes() {
+  var j = 0;
+  var output = new Array(32);
+  for (var i = 0; i < 8; i++) {
+    output[j++] = (ihash[i] >>> 24) & 0xff;
+    output[j++] = (ihash[i] >>> 16) & 0xff;
+    output[j++] = (ihash[i] >>> 8) & 0xff;
+    output[j++] = ihash[i] & 0xff;
+  }
+  return output;
+}
+
+/* Get the internal hash as a hex string */
+function sha256_encode_hex() {
+  var output = new String();
+  for (var i = 0; i < 8; i++) {
+    for (var j = 28; j >= 0; j -= 4)
+      output += sha256_hex_digits.charAt((ihash[i] >>> j) & 0x0f);
+  }
+  return output;
+}
+
+/* Main function: returns a hex string representing the SHA256 value of the 
+given data */
+function sha256_digest(data) {
+  sha256_init();
+  sha256_update(data, data.length);
+  sha256_final();
+  return sha256_encode_hex();
+}
+
+module.exports = {
+  sha256: sha256_digest
+}
\ No newline at end of file
diff --git a/lib/util.js b/lib/util.js
index 292df2a..a18808d 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -1,6 +1,14 @@
 
 function isValidUrl(url) {
-  return /(ht|f)tp(s?):\/\/([^ \\/]*\.)+[^ \\/]*(:[0-9]+)?\/?/.test(url);
+  return isOnlineUrl(url) || isDataUrl(url);
+}
+
+function isOnlineUrl(url) {
+  return /(ht|f)tp(s?):\/\/([^ \\/]*\.)+[^ \\/]*(:[0-9]+)?\/?/.test(url)
+}
+
+function isDataUrl(url) {
+  return /data:image\/(\w+);base64,(.*)/.test(url);
 }
 
 /**
@@ -63,6 +71,8 @@ function equal(a, b) {
 
 module.exports = {
   isValidUrl,
+  isOnlineUrl,
+  isDataUrl,
   equal
 };