Abstract: In real-time substructure testing (RST) with a hydraulic actuator as the loading devices, there is an inevitable time delay of actuator response. This paper introduces a bilinear step response model based on the basic dynamics of an actuator. With this model, the effects of time delay and compensation of integration methods in RST are analyzed using spectrum radius method. The specific time stepping methods under investigation are the operator-splitting method and the central difference integration method. The analysis results show that the time delay will reduce the stability of RST response, while the 3rd-order polynomial compensation can improve the stability effectively. The results also show that the stability of the operating-splitter method is better than that of the central difference method.