Abstract: Aiming at maneuvering point targets flying in the sky,a uniform missile-borne passive system(include infrared passive system and passive radar system) distance estimation model with Markov jump parameters is built by using the spectra radiation illuminance of the targets.Based on the optimal filtering theory of structure stochastic jump systems,a passive system distance estimation algorithm is presented.In view of the rapidity of the algorithm,two simplified calculations are derived.The computer simulation verifies the validity of the algorithms, and the simplified algorithm is high real-time.