Abstract: High-strengthed TRIP800 steel plates of 1.8 mm thickness were spot welded, and then shear testing was performed on joint, and hardness distribution, microstructure and fracture morphology were analysed. The results show that there were not obvious defects in welded joint under testing process conditions, and the joint owned good shear property. The microstructure of joint fusion zone was strip martensite, and the microstructure of joint heat affected zone were martensite, ferrite and high-remperature tempered banitte. The shear fracture showed ductile tear characteristics.