In this paper,the microstructure,mechanical properties at room temperature and high temperature,and the fracture morphology of dissimilar welded joints between HP-Nb M heat-resistant steel and 15CrMo steel,Cr18Ni10Ti stainless steel were analyzed by the optical microscope, electronic universal testing machine,and scanning electron microscope. The results show that the microstructure change occurs in the heat-affected zone of 15CrMo,and the ferrite-pearlite structure transforms into the ferrite-martensite structure. Much α-phase precipitates in the heat-affected zone of Cr18Ni10Ti stainless steel. The yield strength of these two welded joints is higher than the base metal,but the percentage elongation after fracture is lower. Under high temperature,higher tensile strength of these two welded joints was obtained with the increase of strain rate.