diff --git a/changelog_unreleased/mdx/pr-6398.md b/changelog_unreleased/mdx/pr-6398.md
new file mode 100644
index 000000000..8d04c8294
--- /dev/null
+++ b/changelog_unreleased/mdx/pr-6398.md
@@ -0,0 +1,21 @@
+#### MDX: fix JSX Fragment format incorrectly ([#6398](https://github.com/prettier/prettier/pull/6398) by [@JounQin](https://github.com/JounQin))
+
+Previous versions format JSX Fragment incorrectly in mdx, this has been fixed in this version.
+
+<!-- prettier-ignore -->
+```md
+<!-- Input -->
+<>
+    test   <World        />   test
+</>       123
+
+<!-- Output (Prettier stable) -->
+<>
+test <World        /> test
+</> 123
+
+<!-- Output (Prettier master) -->
+<>
+  test <World /> test
+</> 123
+```
diff --git a/src/language-markdown/mdx.js b/src/language-markdown/mdx.js
index a72597777..f8bab299d 100644
--- a/src/language-markdown/mdx.js
+++ b/src/language-markdown/mdx.js
@@ -26,7 +26,7 @@
 
 const IMPORT_REGEX = /^import\s/;
 const EXPORT_REGEX = /^export\s/;
-const BLOCKS_REGEX = "[a-z\\.]*(\\.){0,1}[a-z][a-z0-9\\.]*";
+const BLOCKS_REGEX = "[a-z][a-z0-9]*(\\.[a-z][a-z0-9]*)*|";
 const COMMENT_REGEX = "<!---->|<!--(?:-?[^>-])(?:-?[^-])*-->";
 const EMPTY_NEWLINE = "\n\n";
 
diff --git a/tests/mdx/__snapshots__/jsfmt.spec.js.snap b/tests/mdx/__snapshots__/jsfmt.spec.js.snap
index f5dc83bc8..d15f9aed2 100644
--- a/tests/mdx/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/mdx/__snapshots__/jsfmt.spec.js.snap
@@ -265,6 +265,12 @@ printWidth: 80
 
 ---
 
+<>
+    test   <World        />   test
+</>       123
+
+---
+
 | Column 1 | Column 2 |
 |---|---|
 | Text | <Hello>Text</Hello> |
@@ -299,6 +305,12 @@ printWidth: 80
 
 ---
 
+<>
+  test <World /> test
+</> 123
+
+---
+
 | Column 1 | Column 2            |
 | -------- | ------------------- |
 | Text     | <Hello>Text</Hello> |
@@ -342,6 +354,12 @@ semi: false
 
 ---
 
+<>
+    test   <World        />   test
+</>       123
+
+---
+
 | Column 1 | Column 2 |
 |---|---|
 | Text | <Hello>Text</Hello> |
@@ -376,6 +394,12 @@ semi: false
 
 ---
 
+<>
+  test <World /> test
+</> 123
+
+---
+
 | Column 1 | Column 2            |
 | -------- | ------------------- |
 | Text     | <Hello>Text</Hello> |
diff --git a/tests/mdx/jsx.mdx b/tests/mdx/jsx.mdx
index 47b911be6..85961c373 100644
--- a/tests/mdx/jsx.mdx
+++ b/tests/mdx/jsx.mdx
@@ -27,6 +27,12 @@
 
 ---
 
+<>
+    test   <World        />   test
+</>       123
+
+---
+
 | Column 1 | Column 2 |
 |---|---|
 | Text | <Hello>Text</Hello> |