Abstract: To optimize welding process parameters,and effectively analyze stress and strain field for further work,16MnR steel used for pressure vessel has been subjected to numerical simulation obtain temperature field by ANSYS with the different welding parameters on 60 mm thick plate.The simulation results and welding experimental results were in good aqreement.It was found that the calculated values of temperature distribution were close to the measured values.The closer experimental feature point to characteristic point of heat source,the more quickly temperature rise and the higher peak temperature reaches.With the weld passes increasing,the interpass temperature rise gradually.The uniform microstructure can be obtained just by careful comtrol of the interpass temperature.These reserch results are significant for designers to obtain excellent welding structure.