HILSS (Hardware in the loop Simulation System) is a safe off-line virtual test system that will meet off-line test requirements, reduce development costs and shorten the test cycle. Traditional development methods of the control system will be changed by HILSS, which has been considered as an advanced simulation technology and a convenient method. The construction and development of HILSS of CVT (Continuously Variable Transmission) for vehicles are presented in this paper. The structure and principle of CVT HILSS are analyzed, then the engine model is built based on the engine data of bench test and the best economic and the best dynamic curves of the engine are drawn. The clutch model and the speed ratio control model are built based on the actual structure of the CVT. These models are verified to be practical by the Matlab/Simulink. At last, HILSS platform is built which can make debugging and development of the control system a reality.