Abstract: The spare parts of naval ships are major support for regular and emergent maintenance. The allocation level of spare parts is directly related to the logistic capability and investment. Based on both foreign and domestic study about spare parts allocation, this paper analyzes the ship maintenance system and summarizes the categories for different approaches such as the historical data forecasting method, METRIC theory-based method, and system reliability-based method according to their own theoretical basis and mathematic models. Meanwhile, the advantages and disadvantages of these methods are comparatively studied. Finally, the research directions considering component importance, multi-constraints, and multi-objective optimization, and spare parts sharing strategy optimization are proposed.