Abstract: To study the effects of water stress on the protective enzymes activity and relative water content of soybean leaves, three soybean varieties,‘Heinong 57’,‘Improved 168’and‘Suinong 26’, are used in pot water control experiment. Moderate drought, severe drought and suitable moisture treatment are set up. The results showed that: (1) the activity of superoxide dismutase and peroxidase increased first and then decreased under suitable water condition, and the catalase activity and relative conductivity decreased; (2) the activities of superoxide dismutase and catalase were as follows: moderate drought>severe drought>suitable moisture, and the differences were significant, the peroxidase activity in each period and relative conductivity at seedlingflowering stage were as follows: severe stress > moderate stress > suitable water, and the differences were also obvious. (3) Under drought stress, the activities of peroxidase and superoxide dismutase were as follows: ‘Heinong 57’>‘Improved 168’>‘Suinong 26’, the catalase activity among varieties had no significant difference. In conclusion, under drought stress, the activity of protective enzymes and relative conductivity in spring soybean leaves are higher than that under suitable water condition, reflecting the self-regulation ability of spring soybean to drought environment.