Abstract: The structural dynamic stresses in the process of large area overlaying by using laser cladding and MIG welding methods were observed. The results show that the maximum dynamic stress is much lower than the yield stress of the structure in the process of laser overlaying butgreater than the yield stress in the process of MIG overlaying welding, and the maximum tensile stress which produced in the middle of the structure is 311.27 MPa.The dimension increases 0.4 mm in width after the MIG overlaying welding. The maximum residual stresses measured by hole-drilling method, after the laser overlaying welding or MIG overlayingwelding, reaches about 220 MPa both.