Abstract: The method to calculate the initial stiffness of end-plate joint is proposed by dividing the joint into end-plate in bending, column flange in bending and column panel zone in shear. The initial stiffness of each component is calculated and combined to generate the overall initial stiffness of the joint. Two types of connections are studied: non-stiffened end-plate connection and stiffened end-plate connection. The effect of bolt pretension on joint stiffness and the contribution of column flange to panel zone stiffness are taken into consideration. The accuracy of the proposed method is demonstrated by a comparison with the results from tests and that from finite element analysis. Finally, the proposed method is applied to evaluate the rigidity of the end-plate joints designed by Chinese codes and to investigate the effect of stiffeners on joint stiffness.