Simulation models are increasingly being used to solve more and more complex problems and to aid in decision-making. To provide a realistic and confident simulation environment for users, simulation models have become key components in military simulations. This paper discusses the modeling nature of simulation models, and then the modified validation criteria for measuring the agreements between Subject Matter Experts and simulation models are presented. Furthermore, validation methods such as graphical comparison, feature analysis, face validation, confidence interval and hypothesis tests of three types errors, are discussed according to the validation metrics of simulation models. Simulation models could be validated based on the proposed validation process effectively. The proposed process could be applied to the simulation systems and solve many VV&A difficulties. Example of the mass moment missile, illustrates the validity of the proposed process.