According to trajectory tracking problem in terrain survey mission, trajectory scheduling and control method is researched for unmanned underwater vehicle (UUV). Cross track error and line of sight combined guide is used for trajectory indirect control. In order to ensure precision, track and heading error are both used to switch guide method. Meanwhile, inserting medi-task scheduling strategy is used to improve the survey effect. Compared with ordinary strategy, it can improve stability while task switching and reduce overshoot and oscillation. At last, the results of lake trial are present, which show that combined guide method is effective. By compare with two different scheduling trials, the results indicate that medi-task scheduling strategy can improve control character while task switching, and increase control precision, which is advantageous for terrain survey.