基于最优控制理论二次性能最优的条件下推导最优导引律的解析解通常是困难的。该文基于二阶制导系统，利用许瓦兹不等式能很容易地推导出一种用解析形式表示的最优导引律。该导引律通过估算剩余飞行时间、测量导弹速度及其导数，能实现零脱靶拦截，且制导系统所需的机动能量与比例导引相比要小得多。 It is usually difficult to derive the analytical solution of the optimal guidance law based on the optimal quadratic performance of the optimal control theory. Based on the second-order guidance system and using the Schwarz-do inequality, this paper can easily derive an optimal guidance law expressed in analytical form. The guidance law can achieve zero off-target interception by estimating the remaining flight time, measuring the missile velocity and its derivatives, and the maneuvering energy required by the guidance system is much smaller than that of the proportional guidance.