Aimed at the problems of low welding efficiency, high labor intensity and unstable welding quality of longdistance oil and gas pipelines, a pipeline fullposition welding robot was developed. According to the characteristics of field construction, the structure of the welding robot was determined by using the modular design method,including the walking mechanism, welding torch adjustment mechanism and wire feeding system. The structural characteristics and working principle were analyzed. Kinematics equation of the robot was established according to the mechanical model, the simulation and experimental study were carried out. The simulation results show that the robot can complete the welding of the corresponding wall thickness steel pipe, and the welding quality is good