In order to solve the problem of airborne gun attack area， this paper proposes an improved backtracking method and applies it to the study of airborne gun attack area. First， according to the definition of attack area of helicopter airborne guns， the mathematical models of the helicopter and the airborne gun are comprehensively considered. The target trajectory is predicted based on the least square method. And the aiming hit equation is established for the air to ground target attack problem. Second， considering the constraints of armed helicopters and air guns， the problem of solving the attack area is transformed into a space tree optimization problem. The pruning function and the search priority function are introduced. An improved backtracking method is proposed to solve the boundary of the attack area of airborne air guns. The search of redundant nodes inside the attack area is omitted. And the search efficiency of the attack area is improved. Finally， the feasibility and effectiveness of the proposed method are verified by simulation.