Abstract: The seam tracking precision and the welding speed of master-slave robot remote welding should meet the requirement during welding.However,when manual operator control the master-slave robot remote welding system,the reason why seam tracking precision does not meet the requirement of the welding is unknown.In this paper,a master-slave robot remote welding system was built consisting of a master manipulator with six degrees of freedom(DOF),an industrial computer control system,a slave MOTOMAN HP3J robot and laser sensor system.The factors that affected the tracking precision of straight welding seam were analysed based on the ergonomics.The experiment results show that the longer the reaction time of operator,is the lower tracking precision,and the welding speed should be controlled by the robot to improve the welding process stability and welding quality.