Abstract: How laser pretreatment can improve soybean seedlings' cold acclimation is studied in the view of energy transformation,biomembrane integrality and oxygen free radical injury.The results show that pretreatment of soybean seeds with He-Ne laser enhance not only the seeds' content of ATP but also seedlings' cold acclimation during cotyledons to primary leaves stage.Pretreatment groups' seedlings at 3℃～5℃ temperature have much higher enzyme activities and content of catalase(CAT),peroxidase(POD),superoxide dismutase(SOD),amylase(AML) and soluble protein content than those in control.Pretreatment of soybean seeds with laser also decreases the rate of product of O2-,the accumulation of MDA and the conductivity rate at low temperature.