The terrain-avoidance ( TA) algorithm is very important, when the cruise missile based on laser-forward-looking radar avoids the terrain obstruct automatically. For the TA algorithm, the concept of flying-vector-triangle is proposed. 针对基于激光前视雷达的巡航导弹在巡航阶段实现自主地回避地形障碍物这一课题,在地形回避算法中,提出了飞行矢量三角形的概念。