Abstract: In the research on the collapse of the structures under strong earthquake, the nonlinear dynamic behavior of tall reinforced concrete (RC) structures is influenced by the characteristics of the foundation soil. The assumption of a fixed-base model for this type of structure might not adequately represent their seismic response. Therefore, the seismic performance evaluation should take into account the soil-structure interaction (SSI). In this study, the seismic performance of a 10-story RC frame with fixed-base and flexible-base conditions is evaluated. The characteristics of the flexible-base models cover three types of soils, namely, soft soil, medium soft soil and medium hard soil. The ATC-40 spring model is adopted to represent the soil condition. The analysis results reveal that the roof displacement will be magnified when considering SSI. The inter-story drift angle in the first story will be increased obviously, and will be smaller in the second and above stories compared with the fixed-base model. The failure point will change from the bottom to the top of the column in the first story compared with the fixed-base model, while the distribution of plastic hinges will be concentrated in the lower stories, which reduces the capacity resistance of the frame.