The national defense industry is the natural carrier of the integration of military and civilian development. With the deepening development of military and civilian integration, the connection between military enterprises and civil enterprises is becoming closer and closer. How to analyze and solve the problems of communication and integration between military and civilian is to enhance the needs of the theoretical level, but also how to speed up the integration of military and civilian development of the real problem. Based on the theory of international trade, this paper analyzes the analogy between military and civilian integration and trade between the two countries. Based on the gravitational model of trade flow, this paper constructs the measure model of the integration level of national defense industry. That the integration of military and civilian development should follow the "can be financial integration, should be financial integration" principle, from the reality, can not ignorant pursuit of the degree of integration.