Abstract:The reduction of relative water potential (ΨW) of cotton seedling leaf were retarded and the cotton drought resistance was improved obviously by seed immersion in 0.01 mol/L CaC12 solution and spraying the leaves of cotton with the same solution under drought soil condition. The decrease ranges of the chlorophyll content, photosynthetic rate, respiratory rate and of the activities of superoxide dismutase (SOD) and Catalase (CAT) were less than those of the control. The increase ranges of malonadehyde (MDA) content and the relative cell membrane permeabihty were lower than those of the control. The results showed that seed immersion in and spraying leaf with CaCl2 solution can increase the ability of moisture conservation and various phsiological activities in the cotton leaf.