In order to solve the problems of detection probability change caused by the dynamic change of radar cross section (RCS) during the movement of stealth target and incomplete consideration of the change of detection performance of AWACS in the calculation of detection area of AWACS, a method of calculation of detection area of AWACS is proposed based on the detection probability. The changes in detection probability caused by dynamic changes in RCS during stealth target movement are discussed, and an early warning aircraft detection area calculation model is established. Distinguishing between runway-shaped, figure-of-eight, circular, triangular and other common cruise routes of AWACS, the total coverage area and strong area of AWACS at a specific altitude layer are simulated and calculated, and its feasibility is verified. The results show that the method can effectively calculate the total coverage area and strong effect area of AWACS flying at different altitudes according to different cruise routes.