diff --git a/src/core/func/__test__/string.test.js b/src/core/func/__test__/string.test.js
new file mode 100644
index 000000000..94ecb9932
--- /dev/null
+++ b/src/core/func/__test__/string.test.js
@@ -0,0 +1,19 @@
+/**
+ * @author windy
+ * @version 2.0
+ * Created by windy on 2020/6/5
+ */
+describe("dateFunctionTest", function () {
+
+    before(function () {
+
+    });
+
+    /**
+     * test_author_windy
+     */
+    it("getWeekNumber", function () {
+        expect(BI.replaceAll(null, "A", "b")).to.equal(null);
+        expect(BI.replaceAll("A", "A", "b")).to.equal("b");
+    });
+});
\ No newline at end of file
diff --git a/src/core/func/string.js b/src/core/func/string.js
index a480b1ee3..c2d5aeb14 100644
--- a/src/core/func/string.js
+++ b/src/core/func/string.js
@@ -81,7 +81,7 @@ _.extend(BI, {
      * @returns {String} 替换后的字符串
      */
     replaceAll: function (str, s1, s2) {
-        return str.replace(new RegExp(s1, "gm"), s2);
+        return BI.isNull(str) ? str : str.replace(new RegExp(s1, "gm"), s2);
     },
     /**
      * 总是让字符串以指定的字符开头