Abstract: Effects of different temperature treatments on cell membrane permeability and protective enzyme system of Solanum nigrum L.seedlings were studied.Results showed that under 300 μmol/（m2·s）light，with decrease of temperature，POD activity was increased，SOD and CAT activity were decreased，MDA content was increased，and permeability of cell membrane was increased.It showed that seedlings of Solanum nigrum L.have started their own stress mechanism in low temperature environment，showing an emergency response to stress，and oxygen free genes generated in the body exceed scavenging ability of antioxidant system，causing membrane lipid peroxidation and membrane system damage.