diff --git a/README.md b/README.md
index 095a519d..790b5ab2 100644
--- a/README.md
+++ b/README.md
@@ -325,7 +325,7 @@ TODO
 - [ ] Code block recognition within the text
 - [ ] Table of contents recognition
 - [x] Table recognition
-- [ ] Chemical formula recognition
+- [ ] [Chemical formula recognition](docs/chemical_knowledge_introduction/introduction.pdf)
 - [ ] Geometric shape recognition
 
 # Known Issues
diff --git a/README_zh-CN.md b/README_zh-CN.md
index e51376da..3589d038 100644
--- a/README_zh-CN.md
+++ b/README_zh-CN.md
@@ -329,7 +329,7 @@ TODO
 - [ ] 正文中代码块识别
 - [ ] 目录识别
 - [x] 表格识别
-- [ ] 化学式识别
+- [ ] [化学式识别](docs/chemical_knowledge_introduction/introduction.pdf)
 - [ ] 几何图形识别
 
 # Known Issues
diff --git a/docs/chemical_knowledge_introduction/introduction.pdf b/docs/chemical_knowledge_introduction/introduction.pdf
new file mode 100644
index 00000000..9ececd8f
Binary files /dev/null and b/docs/chemical_knowledge_introduction/introduction.pdf differ
diff --git a/docs/chemical_knowledge_introduction/introduction.xmind b/docs/chemical_knowledge_introduction/introduction.xmind
new file mode 100644
index 00000000..a73d2c15
Binary files /dev/null and b/docs/chemical_knowledge_introduction/introduction.xmind differ