To evaluate in vitro release and transdermal behaviors of Huoxue Zhitong gel, modified Franz diffusion cell methods was applied to investigate in vitro transdermal absorption of Huoxue Zhitong gel and the content of paeonolan in receptor fluid composed of PEG400%-95% ethanol-water (l:3:6)were determined by HPLC. The results were processed and different equations were fitted. The release law were in accordance with Weibull equation and the fitting equation was In[-1/(1 - Q)] = -0.790 51nt - 1.7012 (r = 0.9809). In 8 hours, cumulative release of paeonol was 85. 18% and the release rate was 2.827 µg . cm-2 h-1. Transdermal actions were consistent with zero-level model fit and the fitting equation was Q(t) = 1.7579t + 0. 7213 (r = 0.9991). In 8 hours, cumulative transdermal rate and transmission rate of paeonol was 54. 85%, 1. 820 µg . cm-2 h-1. So the Huoxue Zhitong gel had a good release and transdermal properties.