Abstract: By using the finite element programme for the axial symmetry heterogeneous material in elastoplastic slate,this paper analyses the local stress state and plastic deformation behaviour in the vicinity of implant notch.The calculated results show that the stress concentration factor at the notch tip remains constant in the elastic range,but decreases with the increase of external load in the plastic range.For the lower strength weld metal,the plastic deformation zone in weld joint extends mainly in the weld metal;however,for the higher strength weld metal,the stress in the weld increases and the plastic zone diminishes.