Abstract: This research analyzes the space luminous environment when missile-borne star sensor is used to image the starry sky. Irradiancies of strays (sunlight, moonlight, earth and atmosphere radiation) at star sensor working height were estimated based on Planck blackbody radiation law. Included angles between the star sensor optical axis and strays at any moment were calculated utilizing the relative astronomy and mathematics knowledge. Considering the effect of strays suppressed by sensor baffle, a real-time model for space luminous environment of missile-borne star sensor was established. The simulation results show that included angles between the star sensor optical axis and strays are identical with the actual situation. The proposed model could conveniently estimate the space luminous environment of missile-borne star sensor in real-time, which would provide a basis of star-chosen strategy and missile launch window.