diff --git a/csst_ms_mbi_img_L1_fits.md b/csst_ms_mbi_img_L1_fits.md
index 12dd72ee2664ced25ec8758ddee69571f2bbf68c..651f0c91ca8ebb939618e444ebead6a3f1f1a3e5 100644
--- a/csst_ms_mbi_img_L1_fits.md
+++ b/csst_ms_mbi_img_L1_fits.md
@@ -13,7 +13,9 @@
 | SIMPLE  | True  | Fits standard | True           | bool | csst_sims |     
 ## HDU1
 
-### Header
+### Header of instrument
+
+### Header of distortion
 
 | keyword   | value                     | comment                       | fallback_value | type | module                  |
 |-----------|:--------------------------|-------------------------------|----------------|------|-------------------------|
@@ -41,3 +43,7 @@
 | DEC_CEN   | 26.72643742371229         | the center of detector in dec | -99                   | f64  | csst_ms_mbi_distortion  |
 | DIST_V    | '1.0     '                | version of distortion         | '0.0'                 | str  | csst_ms_mbi_distortion  |
 | DIST_TOL  | '2022-12-29T16:36:47'     | distortion operation time     | '2022-12-29T16:36:47' | str  | csst_ms_mbi_distortion  |
+
+### Header of position calibration
+
+### Header of flux calibration