Maintenance system planning is an important and difficult issue in the design of aviation materiel, as it should coordinate with the design level and maintenance capability. To explore the issue, maintenance support process modeling and simulation provide an effective way. Aiming at the situation that aviation materiel maintenance system changing from three-level to two-level, at home and abroad, this paper respectively establishes maintenance support process model under each case, in order to explore whether the changing maintenance system is reasonable under each country's current design level and maintenance capability. A typical example is demonstrated afterwards, in the example, a certain type of materiel's effectiveness are evaluated under different maintenance support process according to Monte Carlo simulation, and the appropriate maintenance system is finally determined.