Abstract: The effects of betaine on activities of membrane protective enzymes in wheat seedlings were studied. The results showed that the exogenous betaine could promote the activities of membrane protective enzymes such as superoxide dismutase (SOD) and peroxidase (POD), decrease the accumulation of malonic dialdehyde (MDA), and decrease the leaf relative conductance and saltstress-induced injuries of plasma membrane under 1.2% NaCl stress. All these changes could raise the cell membrane stability and integrity , and the adaptabilities of wheat seedling to NaCl stress.