In view of the problem of large residual stress in laser melting deposition, this paper summarizes the mechanism and the effective methods of eliminating the stress. Based on the principle of electromagnetic field, the method utilising electromagnetic field to assist laser melting deposition is proposed in order to reduce the residual stress. The process of laser melting deposition assisted by electromagnetic field is simulated using ANSYS parametric programming language APDL, and the temperature field and the change rule of residual stress are analyzed. The results show that the axial electromagnetic force can effectively reduce the residual stress in the workpiece. Method of X ray diffraction combined with electrolytic corrosion is used to measure the residual stress, and the test results verify the effectiveness of the assisted electromagnetic field.