With the rapid development of information equipment， the combat style is also changing and improving， and the cross domain distributed operation through air ground coordination will become inevitable. The air combat platform has the advantages of good mobility， broad vision and strong situational awareness， while the ground defense equipment has the advantages of concealed deployment， wide firepower coverage and strong anti-interference ability. Adopting the distributed coordination mode of air and ground can give full play to their respective advantages， improve the utilization rate of equipment of all services and arms， and achieve greater operational efficiency. In the future， air ground cooperative operations will be characterized by “three-dimensional unity， air to ground coordination， and multiple divisions in one region”。The necessity of cross domain distributed operation through air ground coordination is put forward in this paper for future battlefield characteristics. The characteristics of cross domain distributed defense are given. The shortcomings of the current defense operation architecture are analyzed， and the specific measures of air ground cooperative cross domain distributed defense are analyzed. The key technologies of cross domain distributed defense are summarized and the development suggestions are given.