Abstract: Pot experiments were conducted to study the effects of selenium on the antioxidant capacity and membrane lipid peroxidation of pakchoi cabbage (Brassica Chinese L.) under salt stress. The results showed that there was no significant influence of selenium on the biomass of pakchoi cabbage; The activities of glutathione peroxidase, hydrogen peroxidase, peroxidase and superoxide dismutase increased significantly with application of 0.9 mg/kg selenium. The content of glutathione, selenium and the antioxidant capacity of pakchoi cabbage also increased significantly with Se treatment. The contents of free radical and abicin dial aldehyde and the membrane lipid peroxidation of pakchoi cabbage decreased significantly by Se addition. Selenium inhibited the permeability of plasma membrane of pakchoi cabbage. It is suggested that selenium application might improve the resistance of pakchoi cabbage to salt stress.