• A numerical simulation platform is established to realize the active truncation model test method of deep-water mooring system, including the integrating of kinematics model, actuator model, and control algorithms of Stewart platform. • The method of cubic spline interpolation is proposed to solve the time delay compensation of actuator motion control through compensating the input signal of actuator. • The influences of time delay value, history data points, noise and sample frequency are investigated to find the reasonable parameters affecting compensation effect. A numerical simulation platform is established to realize the active truncation model test method of deep-water mooring system, and the time delay is focused in this paper. The Stewart platform is chosen as the actuator aiming to realize the motion control of truncated point in mooring line. The corresponding kinematic model and motion control strategy of actuator are established. The method of cubic spline interpolation is proposed to solve the time delay compensation of actuator motion control, the influences parameters affecting compensation results are compared, and the corresponding compensated effects are verified. Through compensating the input signal of actuator, the real-time motion tracking accuracy of the truncated point of mooring line is effectively improved, which have contribution to the success of following physical experiments. [ABSTRACT FROM AUTHOR]