The existing seismic test of the RC column reinforced with steel strips is used as the simulation object, and then its seismic performance is analyzed by ABAQUS. The establishment of the corresponding finite element model is completed by selecting the appropriate constitutive model and interface treatment criteria, and the error between the simulation results and the test results is small, so the modeling method is feasible. Subsequently, with the change of size, the influence of the seismic bearing capacity and reinforcement effect of the steel strip were researched. From the results, it can be seen that: When the size increases, under steel belt reinforcement the improvement of the seismic bearing capacity increases first and then decreases. And based on the finite element analysis, a method for calculating the bearing capacity of RC columns reinforced with steel strips, which takes into account the effect of size effects, is proposed. The average error between calculation and simulation is within 7%, so this method is feasible.