Abstract: SRC columns are widely used in high-rise buildings because of their good seismic performance. To investigate the influence of steel ratio on its seismic performance, low-cyclic loading test was conducted on two big sized encased cross-section steel reinforced high-strength concrete circular columns. The failure characteristics, hysteresis curves, bearing capacity, deformation, stiffness degradation process and energy dissipation of the two specimens were analyzed. ABAQUS software was used to simulate the seismic performance of the specimens, and the influence of parameters such as axial compression ratio, concrete strength, reinforcement ratio, flange thickness and loading direction on the seismic performance of the specimen was analyzed. Results show that the failure of the two specimens is mainly bending, the hysteresis curves are full and the bearing capacity decreases slowly. With the increase of the steel ratio, the bearing capacity increases, stiffness degrades slowly, and seismic performance is good. With the increase of the axial compression ratio and concrete strength, the peak displacement gets smaller and the peak load increases. After the peak load, the bearing capacity decreases quickly and the ductility is poor. When the reinforcement ratio increases and the loading direction is changed, the increase of peak load is not obvious. After the peak load, the decay rate of bearing capacity remains unchanged, which has little impact on ductility. By increasing the thickness of the cross-section steel flange, the peak load and ductility are improved, and the seismic performance is better. This study provides a reference for the engineering application of the encased cross-section steel reinforced high-strength concrete circular column.