Aiming at the problem that maintenance support capability in aviation equipment maintenance support is difficult to meet the requirement of maintenance support, a new optimization model of aviation equipment maintenance support process is proposed based on Markov decision process and graphical evaluation review technology. Firstly, taking the total maintenance time as the objective function with decision nodes embedded in the GERT network, the MDP-GERT network model of aviation equipment maintenance support process is constructed. Then, by using the strategy iteration and Monte Carlo simulation technology, solving method of the model is given. Finally, the optimization procedure and estimated time of the nitrogen filling process of several aircrafts are obtained through a case study, which verified the feasibility and effectiveness of the model and algorithm. The results show that this model can effectively provide decision support for shortening maintenance support time and improving maintenance support efficiency by optimizing maintenance process.