The steady state and transient performance of the heavy-duty diesel engine with the WGT(WasteGate Turbocharger) was simulated using HiLS(Hardware-in-the-Loop Simulation) system. The HiLS system consists of the dynamometer model and the engine model. They are composed of mean value model which is programmed by the Matlab/Simulink. A real time simulation is possible since the operating system based on the real time is included. Therefore this HiLS system can be used for development of EMS(Engine Management System) functions.