Abstract: According to the definition of the damage index,a seismic damage model with two linearly combined weighting parameters is established for beam-to-column welded connection in earthquake-resistant steel structure and the computation method of accumulative damage index for welded connection under the simulated seismic cyclic loading is proposed in this paper.By using the FEM programming package ANSYS,the FEM model of welded connection is established and the elasto-plastic analysis is performed.The plastic strains of welds in the condition of overmatching and equalmatching weld joint were obtained respectively.According to the obtained plastic strain of weld,the damage index is computed in the condition of overmatching and equalmatching weld joint.The results indicated that the accumulative damage of welded connection in the condition of overmatching weld joint is less than that in the condition of equalmatching weld joint.