diff --git a/demo/oled/test.c b/demo/oled/test.c
index 018ca13..69b440c 100644
--- a/demo/oled/test.c
+++ b/demo/oled/test.c
@@ -126,7 +126,7 @@ void Test_OLED() {
     uint8_t bufx[8] = {0x5F, 0x53, 0x52, 0x4D, 0x6D, 0xB2, 0x4F, 0x4D};
     sprintf(sbuf, "%s:          13.4271m\0", bufx);
 //    OLED_ShowCHString(&oled, 1, 24, sbuf);
-    OLED_ShowCHString(&oled, 1, 24, "姓名学号班级");
+    OLED_ShowCHString(&oled, 1, 24, "姓名学号:2233");
 
     OLED_DrawRect(&oled, 0, 0, 127, 63);
 // };//
diff --git a/lib/src/oled/oled.cpp b/lib/src/oled/oled.cpp
index 4b2c9ea..d51b2d9 100644
--- a/lib/src/oled/oled.cpp
+++ b/lib/src/oled/oled.cpp
@@ -272,10 +272,12 @@ void OLED_ShowCHString(OLED_T *dev, uint8_t x, uint8_t y, uint8_t *str) {
         step = Font_utf8_to_unicode(str, &unicode_letter);
         if (step != 0) {
             Chinese_t *hzk = find_chinese_data(GET_LOW_BYTE1(unicode_letter), GET_LOW_BYTE0(unicode_letter));
-            OLED_ShowCHChr(dev, x, y, hzk);
-            x += Hzk_size;
-            str += step;
-            found = true;
+            if(hzk!=NULL){
+                OLED_ShowCHChr(dev, x, y, hzk);
+                x += Hzk_size;
+                str += step;
+                found = true;
+            }
         }
         if (!found) {
             OLED_ShowChar(dev, x, y, *str, Hzk_size);