Preview control involves using forward road information acquired from preview sensors in designing a controller. Preview control, which is composed of feedback and feed-forward input parts can lead to better performance than feedback control alone. In this paper, application of the preview control based on the active suspension to tracked vehicles will be introduced. The suspension unit of the tracked vehicle is in the form of a trailing arm type to increase the wheel travel. Because the preview control has been developed for the linear time-invariant system, a linearized model of the system is required. A linear model of the tracked vehicle, which the preview controller is designed based upon, is generated without considering the dynamics of the track elements for simplification. On the other hand, the nonlinear model, which the performance of the controlled system is investigated based upon, is generated by using $Recurdyn^{TM}$, commercial software. The nonlinear model includes nonlinear damping and stiffness characteristics of hydraulic suspension units(HSUs). From the simulation results for RRC 9, performance enhancement of the preview control will be shown in terms of ride comfort by using ISO 2631 under the assumption that actuators are ideal and the velocity of the vehicle is constant.