Abstract: K.pygmaea,Gueldenstaedtia diversifolia,and A.rivularis of the three typical plants in alpine meadow were selected as the research objects.The distribution characteristics of organic acids in the root exudates were analyzed by high performance liquid chromatography, and the detected organic acid components were added to the soil and cultivated for 21 days, and their effects on the main nutrients and enzyme activities in the soil were studied, in order to explore the organic acid of root exudates regulation mechanism of soil productivity.The results showed that lactic acid, acetic acid, citric acid and fumaric acid were detected in root exudates of three plants.Lactic acid was detected in the roots of three plants, with concentrations of 7.02,13.25,4.84 mg·L^-1,respectively.Acetic acid was detected in K.pygmaea and A.rivularis,and the concentrations were 19.32,7.61 mg·L^-1,respectively.Fumaric acid was detected in K.pygmaea and Gueldenstaedtia diversifolia,with concentrations of 0.32,0.39 mg·L^-1 respectively.Only citric acid was detected in root exudates of K.pygmaea with concentrations of 5.24 mg·L^-1.Different organic acids significantly increased the contents of available nitrogen and available phosphorus in soil, and showed different concentration effects（P＜0.05）.The activities of soil urease, sucrase and catalase increased with the increase of lactic acid and fumaric acid concentration, and decreased with the increase of acetic acid concentration.Organic acids promoted the activities of soil urease, sucrase and catalase, except that high concentration(20 mg·L^-1) of acetic acid inhibited the activity of soil catalase.The results showed that the organic acids in root exudates were beneficial to increase the content of main nutrients in soil, promote soil enzyme activity and improve soil productivity.