Experiment results of RC beam-column subassemblage show that the slippage of the longitudinal bar within joint and shear deformation of joint have significant influence on the seismic behavior of the subassemblage, but this kind of joint inelastic deformations has always been ignored in the seismic response analysis of RC frames.In order to simulate the effect of the inelastic deformations of beam-column joints, a zero-length section element was combined to the ends of the beam based on the fiber model.Longitudinal bar slippage was modeled with stress-slippage constitutive model, while stress-equivalent slippage constitutive model was adopted to simulate longitudinal bar slippage and joint shear deformation simultaneously.Nonlinear responses of a typical RC planar frame under rare earthquake excitations were investigated, and the effect of joint inelastic deformations on the global and local responses of the frame was analyzed contrastively.The results show that the maximum top displacements and maximum inter-story drift ratios increase or change slightly, the quantities of the plastic hinge of the beam and the column ends decrease, and the rotation ductility demand of the beam and the column decreases as a whole when joint inelastic deformations are considered.There is a certain safety margin for the joints of the frame to avoid shear failure.Ignoring joint inelastic deformations will result in significant errors if the seismic response of RC frame is large, and the ordinary finite element model of ignoring joint inelastic deformations can be adopted if the seismic response of the structure is relatively small.