In order to comprehensively improve the power, economy and emission performance of land and marine diesel engine under low and medium speed conditions, the engine performance test bench was built. From three aspects of supercharging system, combustion and overall performance, the effects of four supercharging modes on the performance of diesel engine were compared, including low-pressure stage supercharging, high-pressure stage supercharging, two-stage supercharging and two-stage sequential turbocharging. The results show that, compared with other supercharging modes, the two-stage sequential turbocharging mode can significantly increase the intake air flow without causing a significant increase of supercharging pressure and the in-cylinder maximum combustion pressure is far away from the limit when diesel engine operates during propulsion at low and medium speed. Therefore, the appropriate increase of injection amount is feasible to achieve a higher torque output under the low and medium speed conditions. Although the NO_x emission increases slightly under high temperature and oxygen-enriched combustion condition, the two-stage sequential turbocharging mode obtains the benefit of pump work and the reduction of specific fuel consumption through the reasonable utilization of exhaust energy. Compared with the low-pressure stage supercharging, the pumping mean effective pressure of two-stage sequential turbocharging increases by 0.019 3 MPa and the fuel consumption rate reduces by 4.9 g/(kW·h) under 30% load of propulsion characteristic. Accordingly, two-stage sequential turbocharging is the optimal supercharging matching scheme with low load conditions of diesel engine.