In order to better test the steering gear performance, improve the robustness and stability of the loading system, realize accurate signal tracking by the electric load simulator and suppress the excess torque, a high-order nonlinear adaptive terminal sliding mode control strategy was proposed in which parameter changes and disturbances effects were avoided. Considering the steering gear as a disturbance input, the load simulator system was established as a two-input single-output nonlinear system. The state equations of the load simulator and the nonlinear mathematical model were established. Based on this model, an adaptive terminal sliding mode control strategy was proposed. The Lyapunov function was used to prove the asymptotic stability and finite-time convergence of the closed-loop systems. The effectiveness of this control strategy was verified by Simulink simulation. The results show that compared with the ordinary sliding mode control, the tracking accuracy is higher and the residual torque is also well suppressed.