In order to solve the problem of helicopter′s route planning under the environment with complex terrain and threats,an improved pigeon-inspired optimization is proposed,in which the threat heuristic mechanism is integrated. The new algorithm makes full use of the known threat information in combat zone and takes it as the feedback information for guiding the flight,which can enhance the directivity of an individual during searching. The searching space constructed by allowed lists of way points can compress the searching space and ensure feasibility of the planned route. The simulation results show that the proposed method can effectively obtain the optimum route for the helicopter,which has the capability of terrain avoidance and threat avoidance.