To make the cost of a mission minimum, the scouting mission planning system of a UAV should decide the height, velocity, time and payload of the UAV based on the its capability, payloads, the mission information and threat information.We established a cost function according to the scouting mission of the UAV, and obtained the weighted sum to each factor by using analytic hierarchy process (AHP).Then, we built up the corresponding models for each factor, and obtained the scouting mission plan of the UAV by simulation.This plan can make a UAV more effective in mission executing.