Abstract: Experiments were carried out to determine yield strength of 10Ni5CrMoV steels in stable heating and air-cooling process,and effects on residual stress of the yield strength change due to solid-state phase transformation in butt-welded joints of 10Ni5CrMoV steels were investigated by means of numerical techniques.The simulated results show that the temperature-dependent yield strength has great influences on the welding residual stress;the yield strength of the joint in the air cooling cases is lower than that in the stable temperature case due to phase transformation,and the distribution of the simulated weld residual stress is generally in good agreement with the experimental results.