Abstract: The method of modeling for non-linear, non-turbocharger diesel engines based on the Matlab/Simulink is presented. A four cylinder non-turbocharger diesel engine model has been developed through filling and emptying method. Validation has been performed for a 4102 diesel engine. It can be used to control simulation and predict the in-cycle variation of engine parameters. The model has been converted to generic real-time coder program by RTW (real time workshop). The method cuts down greatly the simulation time. As the model adopts the modularized method, it can easily be used for different types of diesels, and can form the basis of non-linear turbocharger diesel engine models.