OBJECTIVE：To establish a method for simultaneous determination of calycosin glucoside ，ononin，calycosin， formononetin，astragaloside Ⅳ，isoastragaloside Ⅱ，cycloastragenol and isoastragaloside Ⅰ in Astragalus membranaceus before and after bidirectional solid fermentation with Cordyceps kyushuensis ，and to investigate the effects of fermentation on the contents of above 8 components in A. membranaceus . METHODS ：HPLC-DAD-ELSD was adopted. The determination was performed on Agilent 5 TC-C18 column with mobile phase consisted of 0.1％ formic acid aqueous solution-acetonitrile （gradient elution ）at the flow rate of 1 mL/min. The column temperature was set at 30 ℃. DAD detection wavelength was set at 260 nm，ELSD evaporation tube temperature was 100 ℃，atomizer temperature was 80 ℃，carrier gas flow rate was 1.6 L/min；injection volume was 15 μL. RESULTS：The eight components had a good linear relationship within their respective ranges of concentration （all R2＞0.999 0）； RSDs of precision ，stability and repeatability tests were all less than 3％（n＝3 or n＝6）；the recoveries was 97.88％-101.32％， and RSDs were 1.22％-2.39％（n＝6）. Setting the content of components in unfermented A. membranaceus as 100％，after bidirectional solid fermentation with C. kyushuensis ，the change rates of 8 components were －98.51％，－96.41％，－94.74％， －96.40％，289.20％，20.25％，－75.05％，562.46％，respectively. CONCLUSIONS ：After fermentation with C. kyushuensis ，the contents of active components as astragaloside Ⅳ，isoastragaloside Ⅰ and isoastragaloside Ⅱ can be increased significantly in A. membranaceus .