Maintainability allocation is an important part of the aircraft maintainability design. Reasonable maintainability allocation can make the aircraft system design economically and effectivelly. In the preliminary design phase, the input of maintainability allocation was not sufficient. In this paper, analytic hierarchy process was used to select the factors of maintainability allocation. Then a maintainability allocation model based on fuzzy comprehensive evaluation was proposed, which included various characteristics of the aircraft design as evaluation factors. Finally, an example was analyzed in detail for the method mentioned above. The result shows that the model can be used to guide the aircraft system maintainability design and achieve the purpose of maintainability allocation.