Aerocraft Operational Integrity (AOI) can be used to show the comprehensive quality attribute of aerocraft in the operational processes. In this study, first of all, the concept of Equipment Operational Integrity (EOI) is shown, while the development process of Aerocraft Operational Integrity (AOI) is introduced. On the other hand, the connotation of AOI is discussed, while the basic characteristics of AOI is introduced, namely objectivity, relativity, randomness and controllability. It also stated that AOI is the basis for Aerocraft Operational Suitability (AOS) and Aerocraft Operational Effectiveness (AOE) in aerocraft operational processes. Meanwhile, three characterizing parameters of AOI is introduced, namely Aerocraft Inherent Readiness Rate, , Aerocraft Inherent Healthy Degree, , and Aircraft Operational Integrity Degree, , while the primary optimum design method of AOI is discussed. Furthermore, the fundamental theory of AOI control is presented, which consists of the concept of AOI control, the connotation of AOI control, the strategy of AOI control and the modes of AOI control. Finally, the foundation of AOI development is analyzed, as well as the research methods of AOI and necessary directions of AOI development in aeronautical and astronautical engineering.