Abstract: The combustion of a diesel engine has a direct impact on its performance.In order to investigate the combustion process of a ω type internal combustion, the relevant model was set up on AMESim, and simulation of this process in the combustion chamber with rated speed was performed.The result shows that the burn process is mainly executed in 20℃A after the piston reaches its upper stop position, and the discharge of carbon and NO is relatively less with rated speed.Pressure and temperature rise rapidly and large amount of heat is send out, which indicate that the combustion process is in well condition.The study can be used as a reference for improvement of the internal combustion of the diesel engine.