Abstract: The equivalent force control method replaces the mathematical iteration with feedback control strategy to solve the nonlinear equations of motion in real-time substructure testing with implicit integration method. For nonlinear structural tests, the equivalent force control method with proportional-derivative (PD) controller will induce a steady-state error of the equivalent force response. This paper chooses the proportional-integral (PI) controller, instead of the PD controller previously used, to eliminate the error. The analytical and simulated results show that the equivalent force control method with PI controller is more effective for nonlinear structural tests compared to that with PD controller.