To meet the increasingly stringent fuel consumption standards and reach the internationally advanced carbon emission levels, the electrification of diesel engine accessories is an important technological approach for energy conservation and emission reduction. Compared with the turbocharging system of traditional diesel engines, the electric boosting system can further improve the charging efficiency of diesel engines and enhance the low-speed torque, transient response, etc. Based on the one-dimensional engine performance simulation software, this paper respectively studies the influence of the electric boosting system on the overall performance of a mass-produced medium-sized diesel engine platform and the corresponding hybrid platform. Firstly, the influence of different layout forms of the electrical boost on the engine performance is studied based on the diesel engine platform. The results show that the series layout form is superior to the parallel one. When the electrical boost is arranged in series at the front, the low-speed torque is increased by 13%, the intake air volume is increased by 44%, and the brake specific fuel consumption (BSFC) is improved by 12%. When arranged in series at the rear, the torque is increased by 11%, the intake air volume is increased by 37%, and the BSFC is improved by 11%. However, considering that if the power consumption of the electrical boost’s motor is sourced from the engine, the BSFC will deteriorate. With the expansion of future diesel engine electrification technologies, the motor can use the electric energy generated by brake power recovery and waste heat recovery. Therefore, the effect of applying the electrical boost in the hybrid vehicle platform is studied. The results show that when the hybrid engine can achieve the same power and torque targets, the series-rear layout form is superior to the series-front one. The specific fuel consumption can be optimized by up to 11%. The rear layout requires the addition of an intercooler, which will lead to an increase in cost. In conclusion, the electric boosting system based on the hybrid platform not only has the advantages of fast dynamic response and solving the turbo lag problem, but also can enhance the vehicle’s power performance and fuel economy to a greater extent by optimizing the matching of the turbocharger and the electric boosting system. The electric boosting system based on medium-sized engines has a more promising commercialization prospect.