diff --git a/README.md b/README.md
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--- a/README.md
+++ b/README.md
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-## Hi there!
\ No newline at end of file
+## File organisation
+Currently, there are 4 parts of docs:
+
+- **API**: contains detailed docs about API designs. (Note that `system_design.md` is a temp draft for discussing high-level design, not for API definitations).
+
+- **knowledges**: contains theorical knowledges/designs for the project (mainly diffusion stuffs).
+
+- **notes4coding**: contains deatiled description for coding, may be useful to coding agents (like codex).
+
+- **papers**: contains useful papers we've found in pdf.