A high performance liquid chromatographic(HPLC)method was developed for the simultaneous determination of monomethyl fumarate(MMF)and dimethyl fumarate(DMF)in Chinese herbal medicine.Samples were extracted with ethyl acetate，purified with NH2-carb solid phase extraction column，separated with C18 column，and determined with diode array detector(DAD).The results showed that there were good linear relationships between peak areas and concentrations of MMF and DMF in the range of 0.025-5.0 μg/mL，with limits of detection(LODs)of 0.015 and 0.020 mg/kg，and limits of quantitation(LOQs)of 0.05 mg/kg and 0.06 mg/kg，respectively.The mean recoveries of MMF and DMF at spiked levels of 0.1，0.2，0.5 mg/kg were in the range of 78.9%-97.3%，with relative standard deviations(RSDs，n=6)of 1.7%-6.0%.This method is sensitive and reliable，and could meet the requirements for simultaneous detections of MMF and DMF in Chinese herbal medicine.