Objective: To investigate purification effect of different types of macroporous resin on water extract of Raphani Semen. Method: The content of sinapine thiocyanate was determined by HPLC

mobile phase of acetonitrile(A)-0.1% phosphoric acid(B) using a gradient elution program(0-15 min

5%-10% A;15-17 min

10%-12.5% A;17-27 min

12.5%-14% A;27-55 min

14%-25% A;55-57 min

25%-70% A;57-70 min

70%~100% A)

detection wavelength 225 nm.With elution rate of sinapine thiocyanate and elution rate of total active ingredients in HPLC fingerprint common peaks as indexes

optimum macroporous resin was screened by comparing purification effect of each model of resin. Result: Effect of each resin on elution rate of sinapine thiocyanate was in order of AB-8>NKA-9>HPD100C>HPD400>X-5>HPD750>HPD722>D101>DM130

but influencing sequence of elution rate of total active ingredients was HPD400>HPD100C>HPD722>AB-8>NKA-9>HPD750>DM-130>D101>X-5. Elution rates of sinapine thiocyanate and total active ingredients by AB-8 resin were 96.39% and 70.03%

respectively. Conclusion: Process of applying AB-8 resin to purity effective constituents from water extract of Raphani Semen was feasible.