The ground clearances of airborne stores is a very important index in the ground compatibility design of airborne stores. It's also one of major factors in determining the scheme of aircraft external carriage. It' s concerned with the aircraft and aircraft external carriage' s safety.But in the military standard of both American and Chinese , the measure of determining the ground clearances is not concerned with the aircrafe's taking - off and landing process on the ground , so it cannot ensure the aircraft and aircraft external carriage' s safety. This article is written for putting forward a scientific measure in determining the ground clearance , according to the' practical use of aircraft , especially through fully considering the aircraft' s taking- off and landing process.