Abstract: The modeling of non-linear non-turbocharger transient-state diesel engine was presented based on Matlab/Simulink. A four-cylinder non-turbocharger transient diesel engine model was developed. Simulation of the dynamic process of abrupt change in throttle (engine load held constant) was implemented. The model has been converted to generic real-time coder program, and simulated by the external method. The method can greatly cut the simulation time. The model can not only be used in parameter demarcation for ECU, but also in the development of complicated control strategies.