This paper addresses the issue of firing compatibility of the naval guns with the air-defense missiles in air defense and missile defense of warship formation. Taking the interception of the anti-ship missile by the naval gun during its full air route as the object of study and based on the quantitative description of airspace resource by using the airspace grid model，this paper adopts the ballistic differential equation to solve the fire control problem and builds a rapid calculation model of fire control units based on the airspace grid. Under the condition of the full-course interception of the anti-ship missile by the naval gun，the occupied airspace resource and time resource by naval gun projectile are calculated.The matching of the occupied spatial and temporal resources is carried out，and a new method based on airspace grid is given，which is helpful to solve the problem of firing compatibility between the naval guns at the launch end with the missiles.