Abstract: Wheat seedlings (4 days old) were treated with Hoagland solution contained NaC1,Na2SO4 and Na2Co3 with the concentrations of 25 mmol/L,50 mmol/L, 100 mmol/L and 200 mmol/L. The content of the organic free radical and the rate of production of the superoxide radical in the leaves of the wheat increased and the membrane leakage increased too. Under the stress of low concertratopm, the effect of NaC1 is greater than that of Na2SO4, but under the stress of the high concertration, the effect is contrary. The effect of Na2CO3 is the greatest. The results showed the good relationships existing between the content of free radical and membrane leakage of wheat leaves: The results showed that the salt stress the increase of the content of free radical, then the free radical affected the membrane leakage through the peroxidation and finally the growth of the wheat was affected by salt stress.