Abstract: Using finite element analysis code ABAQUS, a sequential coupling calculating program on hydrogen diffusion has been developed. Using this program, the effect of as-welded residual stress on the hydrogen diffusion was numerically simulated for the welded joint of a liquefied petroleum gas spherical tank made of 16MnR steel.The hydrogen diffusion without the effect of welding residual stress was also taken into account and compared.This method provides a reference for mastering the criterion of hydrogen induced cracking of welded joint.The result shows that under the welding residual stress field, the hydrogen diffuses and accumulates toward the higher stress zone, attaining stability through a period of time.There is a low hydrogen concentration value around the heat affected zone, where the residual stress gradient and concentration gradient are formed, which can cause the hydrogen long-range diffusion to the high stress zone.