diff --git a/engine/cocos2d/core/renderer/assembler.js b/engine/cocos2d/core/renderer/assembler.js
index 12d30d30..a3109113 100644
--- a/engine/cocos2d/core/renderer/assembler.js
+++ b/engine/cocos2d/core/renderer/assembler.js
@@ -69,7 +69,7 @@ export default class Assembler {
                     if (CC_JSB) comp.node._inJsbDirtyList = false;
                     // setMaterial 中会置 comp._texIdDirty = true;
                     if (!this.isMulti) {
-                        comp._assembler.updateRenderDataForSwitchMaterial(comp);
+                        if (comp._assembler) comp._assembler.updateRenderDataForSwitchMaterial(comp);
                         return true;
                     }
                 }
diff --git a/engine/cocos2d/core/renderer/utils/label/letter-font.js b/engine/cocos2d/core/renderer/utils/label/letter-font.js
index a0766aee..b90534e3 100644
--- a/engine/cocos2d/core/renderer/utils/label/letter-font.js
+++ b/engine/cocos2d/core/renderer/utils/label/letter-font.js
@@ -448,6 +448,10 @@ class LetterAtlases {
         const atlas = letter.atlas;
         const comp = _assembler._renderComp;
 
+        if (!_usedMaterial) {
+            return;
+        }
+
         // 检查是否需要自动切换材质
         if (_needCheckMaterial) {
             _needCheckMaterial = false;
@@ -605,7 +609,7 @@ export default class LetterFontAssembler extends WebglBmfontAssembler {
         const verts = renderData.vDatas[0];
         const floatsPerVert = this.floatsPerVert;
         let texIdOffset = offset + this.texIdOffset;
-        const id = _usedMaterial.material !== _shareAtlas.material ? letter.atlas._tmpId : letter.atlas._id;
+        const id = !_usedMaterial ? 0 : (_usedMaterial.material !== _shareAtlas.material ? letter.atlas._tmpId : letter.atlas._id);
 
         verts[texIdOffset] = id;
         texIdOffset += floatsPerVert;