The electrochemical properties of lithium sulfur batteries at different temperature were investigated by charge-discharge and CV(Cyclic Voltammetry) for probing into the effect of the liquid diffusion process on discharge process of the lithium-sulfur batteries. Surface morphology of sulfur cathodes was observed by SEM(scanning electron microscope). The surface of sulfur cathode was covered by a solid film in low temperature. It suggests that low temperature results in the decrease of diffusion coefficient and diffusion flux of electrolyte for the battery. The discharge properties of lithium sulfur batteries worsens obviously at less than 10 ℃ and below, and the decrease of low plateau specific capacity was mostly the cause of the worsening. The cyclic voltammetry showed that low plateau of discharge process was strongly affected by temperature because it was a diffusion-controlled process which can lead to polarization in cathode. The increase of diffusion resistance of ion in electrolyte caused the passivation of the carbon matrix, the passivation resulted in inadequate reaction of active material in low plateau, that is mostly the cause of the effect of temperature on discharge process of lithium sulfur batteries.