diff --git a/app/src/protyle/export/index.ts b/app/src/protyle/export/index.ts
index 09d6be590..27644c314 100644
--- a/app/src/protyle/export/index.ts
+++ b/app/src/protyle/export/index.ts
@@ -318,6 +318,9 @@ const renderPDF = async (id: string) => {
             item.style.width = Math.min(item.clientWidth, width) + "px";
             item.removeAttribute('data-render');
         })
+        previewElement.querySelectorAll('[data-type="NodeCodeBlock"][data-subtype="mermaid"] svg').forEach((item) => {
+            item.style.maxHeight = width * 1.414 + "px";
+        })
         Protyle.mathRender(previewElement, "${servePath}/stage/protyle", true);
         previewElement.querySelectorAll("table").forEach(item => {
             if (item.clientWidth > item.parentElement.clientWidth) {