According to the airworthiness terms and advisory notice requirement of the State Civil Aviation Administration, the aircraft development unit should show the stall characteristics and recovery characteristics of the aircraft. The test belongs to the limit boundary flight and superenvelope flight of the aircraft, i.e. to verify the extreme flight characteristics of the aircraft. There is a great risk for the prototype aircraft to carry out the test, and there have been many major accidents of aircraft destruction in history. In order to reduce the risk of stall test of prototype aircraft, it is a relatively low risk and high costeffective choice to study stall characteristics using subscaled model free flight test before the test. Through the free flight test of the prototype airplane subscaled model, the flight dynamic characteristics which are not found under the static force test conditions of the model can be captured, and recovery capability of the airplane under the dangerous state can be determined. The dynamic characteristics of a large aircraft with conventional configuration under extreme flight conditions were tested by model free flight test technology before stall flight test, and the departure and developed stable spin of the aircraft under stall/post stall conditions were confirmed. At the same time, it is confirmed that the aircraft has stall recovery capability. The use of “three neutral”, “antirudder, push rod”, “antispin parachute” can force the aircraft to recovery from stall/poststall.