Abstract: The welded joint of heat-resistant steel P91 is used widely at high temperature in power palnt.The distribution of welding residual stress of thick wall pipeline is more complicated, and the welding residual stress has great effect on the creep at high temperature environment.The welding parameters of P91 were optimized by the method of orthogonal experiment design, which uses welding residual stress as the index of evaluation and then the welding residual stress under the optimum welding procedure was simulated by the finite element analysis codes ABAQUS.The distribution of welding residual stress for P91 thick wall pipeline was obtained.The research results show that the effect of welding speed on welding residual stress is the most remarkable.Then the effect of arc voltage, welding current and groove gap on welding residual stress is reduced sequen-tially.The research results can provide the possibility on optimizing welding procedure of high temperature pipe and controlling welding residual stress effectively.