Abstract
In this paper, based on an HEV power train, the influence of the power train's parameters, such as heat engine power, motor power, motor speed range, mechanical gear ratio, battery capacity and power-combined gear ratio etc, on the performance of the vehicle was discussed in detail. As a result, parameters' selection method for the designing of HEV power train was put forward. In order to evaluate the selected parameters' combined influence, a parameters' matching method was also put forward. Finally, through the design practice of a transit bus HEV6440, the feasibility and rationality of this designing method was verified.