It is a waste of resource that excess hardware is chosen to satisfy system requirement without exact evaluation of information process arithmetic, software framework and runtime during the period that weapon system information process scheme is being designed. To resolve this problem, modeling is being done using the tool software firstly, in which the ability of information processor, software flow, data interface and data structure are all simulated. Then Simulation results are analysed according to specifical requirement. At last a conclusion is given that Designing of Minimum margin system that using Simulation and Modeling can ensure the function and capability and reduce cost the at the same time.