Maintainability design is one of the basic works in the development of civil aircraft. The quality of maintainability directly affects the economy and market competitiveness of civil aircraft. The maintainability design of civil aircraft in China started late and lacks systematic forward design methods and technical guidance materials. Applying the practice of system engineering to the design of civil aircraft for forward design can reduce the design workload and rework as much as possible. Implementing the maintainability requirements of stakeholders into the maintainability design of system equipment is crucial to the maintainability design of civil aircraft. Taking the maintainability design of the electrical and electronic cabin of a civil aircraft as an example, the relative importance of the maintainability design requirements is obtained based on the demand weight through demand identification. Then, the maintainability design requirements are implemented into the design of the civil aircraft system equipment by the incidence matrix method. This method adopts forward design, which provides a design idea for designing a well-maintained civil aircraft to meet the needs of users.