Objective To compare the in vitro release and transdermal capability between Erhuang gel paste and its ointment. Methods Strat-M membrane and advanced Franz diffusion cell were used to conduct the in vitro release and transdermal experiment. The content of osthole, the effective component of the key herb radix angelicae tuhuo in the preparations was quantitatively determined by high performance liquid chromatography (HPLC) method to determine the in vitro release rate, transdermal quantity and transdermal rate. Results The transdermal penetration formula of Erhuang gel paste was Ln=0.443 6t+1.350 9, r=0.964 4. The cumulative in vitro release rate, transdermal quantity and transdermal rate were respectively 62.90%, 0.067 2 mg/g and 20.82%. The transdermal penetration formula of Erhuang ointment was Ln=0.205 1t-0.244 7, r=0.995 6. The cumulative in vitro release rate, transdermal quantity and transdermal rate were respectively 77.64%, 0.013 1mg/g and 9.36%. Conclusion The transdermal capability of Erhuang gel paste is obviously better than its ointment, and the gel paste is more convenient to use and is unlikely to cause allergic reactions.