Objective To establish the quality standard of dog-days paste cataplasm. Methods Qualitative identification of Ephedra， Corydalis Rhizoma in the formula was carried out by thin-layer chromatography（TLC）. High performance liquid phase chromatography（HPLC） was used for the content of sinapine thiocyanate in the preparation. Results TLC spots were clear and well-separated without negative interference， the line range of sinapine thiocyanate was 0.0109～0.0872mg/mL， respectively， with good linear relationship with the peak area integral value（r=1.0000）， the average recovery rate was 98.33%， RSD was 2.01%. Conclusion The qualitative and quantitative method with good resolution and was simple， convinient， and reliable with good precision， It can be used for the quality control of dog-days paste cataplasm.