Diesel engine; Super-capacitor; Starter system; Modeling; Simulation Abstract. In order to improve the start-up performance of the diesel engine and the working conditions of batteries, make efficient use of the high instantaneous discharge power characteristics of the super-capacitor as a diesel engine start-up auxiliary power. Taking the YC6J180 types of Yuchai diesel engine as illustration, diesel engine starting process was modeled and simulated by Matlab/Simulink software, and compared with the simulation model of diesel engine starting system added the super-capacitor. The simulation results show that the diesel engine starter system added the super-capacitor as the auxiliary power, the starting performance is improved significantly, meanwhile improve the battery state, and extend its service life.