Aimed at the tactics application problem of missile early-warning information, a cueing capability evaluation method based on trajectory-missile track parameter error estimate by observation data of missile early-warning satellites during boost phase is put forward. By using statistic and reasoning estimate methods, the calculation models in launch point location, burnout point location and impact point location are established, and then the calculation model of goal-cueing region increase-ratio to missile defense system of missile early-warning satellites is designed. A numerical example is given to further illustrate the validity of the method. The cueing capability evaluation of missile early-warning satellites can provide a reference for the setting in important tactics and technical parameters of missile defense system.