In order to determine the influence of different slab models on the seismic performance analysis results for the structure, taking symmetrical normal RC frame structure with interior corridor as an example, the corresponding Pushover analysis models were built using the rigid slab model, elastic slab model and nonlinear slab model(multi-layer shell element) with the SAP2000 software respectively. The results indicate that a dramatic overestimation of seismic capacity can possibly occur for the symmetrical normal RC frame structure with interior corridor based on the elastic or rigid slab model adopted in Pushover analysis, leading to an unsafe design. To overcome this shortcoming, an improved frame structure was proposed through replacing the RC column upper end with a square steel tube, and the corresponding Pushover analysis was also performed. It shows that the improved frame has a better seismic capacity than the normal frame after reasonably designing the column upper end with a square steel tube, and the evaluations of seismic capacity based on the elastic slab model and the nonlinear slab model are close to each other for this improved frame.