Abstract: An experiment was conducted to study the effect of exogenous Putrescine on membrane lipid peroxidation and soluble organic osmoticum in wheat seedling leaves under drought stress induced by polyethylene glycol (PEG-6000). The results showed that the soluble sugar contents, Free proline contents and free amino contents were markedly increased that the ones were 1.73 times, 9.51 times and 1.5 times than that of control, malondialdehyde（MDA）contents and membrane permeability（PMP）were significantly decreased, which were 82% and 84.5% lower than those of MDA and PMP in the control, the grade of membrane lipid peroxidation was significantly reduced. The above results indicate that exogenous Putrescine could improve osmotic adjustment ability of winter wheat seedling leaves under drought stress and increase drought tolerance of plant.