The invention relates to a navigational star screening method for star sensors, which includes the following steps: (1) according to the limiting magnitude of a star sensor, the stars of the original star catalogue of the whole celestial sphere are filtered and a star number threshold Nth is determined; (2) the number of the remaining stars of the star sensor in the field of view of the current sky area is set as N; if N is less than or equal to Nth, then all the remaining stars are chosen as navigational stars, and step 3 is executed; and if N is greater than Nth, then the navigational stars in the field of view of the current sky area are segmented and screened by a multi-scale image plane; (3) after the navigational stars in the field of view of the current sky area are screened, the star sensor turns to the next direction to repeat navigational star screening in step 2 until the whole celestial sphere is traversed. The multi-scale image plane segmentation and screening method adopted in the invention can be adapted to the variation in the star numbers of different sky areas to delete the redundant stars of sky areas with high star distribution density and keep all the stars of low-density sky areas, and moreover, the distribution of the screened navigational stars is even.