diff --git a/README.md b/README.md
index 8368daa7c4b491c3c3762b3069d3a470d8e2fdf0..7d55138293884cbc06e31559f5cbc1ec8be3da5e 100644
--- a/README.md
+++ b/README.md
@@ -28,7 +28,9 @@ The GitHub repository is the real repository where the development happens. The
 
 **IMPORTANT: For detailed documentations, please refer to the `docs` directory.**
 
-This repository contains mainly two parts, `kernel` and `crates`.
+This repository contains mainly three parts, `kernel`, `crates` and `test_preliminary`.
+
+**For preliminary test related information, please refer to the `README.md` from the `tests_preliminary` directory.**
 
 If you are viewing vendored branch from gitlab, there is also a `third_party` directory, which contains some third party code that the kernel depends on.