Abstract: The paper studies resistance projection technology of Fe-C-Cu-Ni-Mo system high strength P/M parts and the influence of heat treatment before and after welding on welding strength. The results show that with appropriate welding criterion,P/M products exhibit superior weldability. The optimum welding parameters under the conditions of present experiments are:electrode pressure P=0.3MPa,welding voltage U=6.0V and welding time=0.55s. The pretreatment before welding is unfavourable for improving welding properties.Quenching at 860℃and tempering at 200℃ after welding is favourable for imoroving microstructure in welding area and enchancing welding strength. Resistance projiction welding technology has been successfully used for a pair of parts in VE distributing pump of car diesel engine.