For the growing importance of future emission restrictions and the expanding requirement for a better fuel economy, the internal combustion engines are forced to be improved for the high strengthening direction. However, the heat loads of the engine is increasing according to the increasing of engine speed and power density, hence, the cooling system is faced to more challenge. For the cooling system is one of the key system which has more effect on the engine efficiency, fuel economy, and exhaust heats; optimize the matching control cooling system becomes one of the key technology to improve the engine performance. In this paper, several overall schemes of the cooling system are analyzed and discussed, and then one design scheme is determined to the optimal for the current diesel engine. A whole engine system is established by the software GT-Power, and the cooling system in the engine system is established by GT-Cool based on the above optimal scheme. During the simulation, the influence on the heat dissipating capability brought by the control parameters, injection advance angle, power, and torque are investigated. At last, the requirement of the heat released under full conditions is analyzed, and the relationship of the fuel consumption and the control parameters is investigated.