The spray model is the main part of IC engine CFD software, and it is composed of various sub-models. Careful validation of the individual breakup models and the availability of proper boundary conditions at the injector exit served as major prerequisites for the successful analysis and optimization of pressure sprays in diesel as well as in gasoline engines. The nozzle flow model used to describe the high-pressure diesel cavitating flow was discussed. And also, WAVE model, KH-RT model, Huh-Gosman model and LISA model， all based on the surface wave instability theory were discussed. The application of these models could largely improve the spray simulation accuracy in theory. The model coefficients need adjusting in order to match the experiment data.