Abstract: To Addresse the issues of relatively small total area of high-efficiency zone in full operating range of the engine and poor dynamic responsiveness, a narrow-domain high-efficiency equivalent consumption minimization strategy（ECMS） control strategy for power-split hybrid commercial vehicles was proposed. A vehicle system model of the power-split hybrid commercial vehicle was independently developed, and the influences of the narrow-domain high-efficiency control strategies for diesel engines, performance optimization of the diesel engine, and main reducer ratio optimization on fuel consumption and emission performance were analyzed. The results show that under the China heavy-duty commercial vehicle test cycle for light truck（CHTC_LT） standard cycle conditions, with the optimized control strategies and parameters, the fuel consumption of the vehicle system decreased by about 10.27%, HC+CO emissions reduced by about 19.30%, NO_x emissions increased by about 4.50%, and particulate matter（PM） emissions decreased by about 23.25%, compared with that before optimization. The optimization scheme not only can improve the vehicle’s fuel economy but also achieve a significant improvement in emission performance.