In this study, Pinus koraiensis seedlings were grown under elevated CO2 (500 and 700 micromol x mol(-1)), and the hydrolase activities in 0 - 10 cm soil layer were determined. The results showed that compared with those under ambient condition, the activities of soil protease, urease, amylase and phosphatase under elevated CO2 increased significantly, while invertase activity decreased significantly. Different concentration of elevated CO2 had different effects on soil hydrolase activities. 500 micromol CO2 x mol(-1) had more significant effect on soil protease and phosphatase activities, while 700 micromol CO2 x mol(-1) had more significant effect on soil urease, amylase, and invertase activities.