Using water culture and three soybean varieties as materials, the effects of aluminum (Al) on physiological characteristics of soybean were studied. The results showed that Al has the obvious inhibitory effects on the growth of soybean, the contents of proline, MDA and soluble carbohydrate were increased, and the activity of roots was decreased. There were some difference among the responses of three soybean varieties to the stress of Al. Based on the values of Al tolerance, we had calculated , the ability of Al tolerance of the three soybean was showed as follow : Zhechun No.3>Zheqiu No.3>Huachun No.18.