Abstract: OBJECTIVE To establish a method for determinaion of two costuslactone in Muxiang Shunqi pills by quantitative analysis of multi-components by single marker(QAMS) for more perfect quality. METHODS Taking costunolide, as reference, a relative correction factor(RCF) of dehydrocostuslactone was established. Then the RCF was used to calculate the contents of the dehydrocostuslacton. In this way, the calculated value was compared with the external standard method. RESULTS No significant differences were found in the quantitative analysis results of dehydrocostuslacton between external standard method and QAMS method. CONCLUSION The described method is reliable, accurate, and can be used to control the quality of costuslactone of Muxiang Shunqi pills.