Abstract： Objective To study the transdermal absorption of Guanjie Xiyao through rat skin with ferulic acid as the reference material. Methods The contents of HPLC of ferulic acid to rat abdominal skin with TK-12B-type diffusion cell were determined. Results Using this HPLC system,we found the Standard curve was A=0.88 × 10-2C -4.62 ×10-2,r=0.9999,and the average recovery was 97.00%,with RSD of 1.97%.Through the calculation of HPLC data,the contents of Felic acid in Guanjie Xiyao was 9.79 mg(n =4),with RSD of 0.20%.The transversal absorption rate of Guanjie Xiyao within 24 h was 47.12%. Conclusion These results demonstrate that major components of Guanjie Xiyao transdersal absorption were effedtive.Changing the dosage forms and prolonging the time of transdermal can get higher efficacy.