Next-generation vehicles which include Electric Vehicles (EV) and Hybrid Electric Vehicles (HEV) are researched and expected to reduce CO2 emissions in the future. Generally, the main factor to support high efficiency of EV and HEV is the idle stop, motor assistance and regenerative braking. The vehicle mechanism of HEV is complex, compared with conventional internal combustion engine vehicle.Certification test method of gas emissions and fuel consumption is used driving mode, which is currently reflecting the typical driving conditions in the market. And driving mode of certification test is established focusing on the reproducibility of driving by conventional internal combustion engine vehicles. It is necessary to consider that the driving mode for the vehicle used regenerative energy is reflected correctly. And high accuracy certification test method for next generation HEVs is necessary in order to evaluate exhaust gas and fuel economy.In this research, new test bench system which responded to a complicated HEV power-train system was produced, in order to investigate HEV test method including driving mode, certification test method for next generation HEV and the test conditions.The bench system is able to reconstruct almost all of parallel HEV power-train system in test room. The bench system is able to operate real internal combustion engine and real electric motor individually, and apply virtual drive train and vehicle. Therefore, the production of real vehicle is not needed for evaluation.Some of the elements of various HEV systems are modeled at HEV power-train system. It is possible to reproduce virtual HEV in the test room. Without a prototype of HEV, it is also possible to evaluate the vehicle driving, which reflected the performance requirements and control conditions, at HEV power-train system.