为研究反导作战中红外预警卫星系统对弹道导弹主动段弹道的跟踪性能，提出以后验克拉美-罗下界(Posterior Cramer-Rao Lower Bound, PCRLB)为衡量指标，结合8态重力转弯主动段运动模型和双星纯方位无源定位获取的量测量，系统分析了运动建模精度、量测精度、采样周期、测源不确定性下检测概率和虚警数目等因素对跟踪时效性和准确性的影响。仿真算例给出了上述因素对位置和速度跟踪性能的影响程度和规律，可为预警卫星反导作战、战技指标关联建模以及星载探测器优化设计等提供有意义的参考。

To study the ballistic missile tracking performance in boost phase based on infrared early warning satellites system, Posterior Cramer-Rao Lower Bound (PCRLB) was proposed as a measurement index. After modeling ballistic target motion by 8-state gravity turn model and locating target position by dual satellites' bearing-only passive localization, PCRLB was used to evaluate the effects of factors, including target motion model accuracy, measurement accuracy, sampling period, detection probability and false alarm number conditioned by measurement origin uncertainty, on tracking timeliness and accuracy. One simulation example showed the extent and rules of said factors on position and tracking performance of velocity. It can contribute to the anti-ballistic missile operation by early warning satellite, the relationship modeling between tactical and technical indices and the optimal design of satellite-based infrared detector.