Digital mockup(DMU) technology has been playing a more and more important role in the development of civil aircraft. Integrity is one of the main attributes and it is used to describe the completeness of the DMU design. In the development process of DMU, integrity ensures the effectiveness of coordination, inspection and verification based on DMU. At the same time, integrity is important for reducing subsequent design changes. From the aspects of modeling rules, coordination process and management system, several key factors and methods are summarized to improve the integrity of DMU .The methods have a good reference to developing the DMU of civil aircraft for coordination.