Mixed Reality (MR) maintenance is characterized by the unique advantages of low cost, low risk and high efficiency, and is a research hotspot in the field of military equipment support. The concept of MR is introduced, and the composition and the key technology of MR maintenance system are described in this paper. The applications of MR in military equipment teaching and training, battlefield emergency repair and intellectualized maintenance are introduced. The existing problems are analyzed, and the corresponding solutions are given out. Finally, the development trend of intellectualization, standardization and modularization in the systems is pointed out, and the suggestions for its application in PLA are put forward.