使被动寻的导弹在较低的平飞弹道情况下，以较小的俯冲过载和最佳攻击姿态精确命中目标；采用带落角约束的变结构导引律，对弹目距离及距离变化率进行估计，克服被动寻的导弹不能测距的约束，同时使切换开关增益随时间自适应变化以减小俯冲过载；利用某型在研被动寻的导弹的气动参数，对此变结构导引律进行了数学仿真，仿真结果表明，在较低的平飞弹道约束条件下及过载要求范围内，该导引律能以期望落角命中静止与机动的坦克目标，对弹目距离变化率及距离的较大估计误差具有较强的鲁棒性。 So that the passive seeker missiles hit the target accurately with the lower dive overloading and the best attack attitude under the condition of the lower ping-pong ballistic trajectory. By using the variable structure guidance law with the falling angle constraint, the missile distance and distance change rate To overcome the constraint that the passive seeker can not measure the distance while changing the gain of the switch adaptively with time so as to reduce the overburden. By using the aerodynamic parameters of a certain type of passive seeker, the variable structure guided law The simulation results show that the guidance law can hit the target of stationary and maneuvering tank at the desired angle of arrival under the condition of low level flight trajectory constraints and overload requirements, The larger estimation error has stronger robustness.