Abstract: In view of the threat of extra vehicular activity(EVA) charging and discharging effects in the low-orbit plasma environment,the plasma environment characteristic,structural characteristic of international space station(ISS) and its charging and potential state were investigated.The operating conditions of the astronauts during EVA and the crewman's extravehicular mobility unit(EMU) were analyzed.Based on the parameters of human body's electrical parameters,the electrostatic discharge model of space station-astronaut-EMU in the low orbit plasma environment was introduced to investigate the charging and discharging effects of different structural potentials in EVA,and the methods eliminating the hazards of charge and discharge in EVA were also analyzed.A theoretical and technical supports for the protection design of charge and discharge effects in the long-term EVA of Chinese space station'astronauts were established.Finally,some suggestions were put forward for the researches to protect China's space station from the charge and discharge effects in EVA.