Aiming at the problem of localizing and grasping targets by an astronaut assistant robot, developing assisting staff to complete specific tasks, and using a self-built visual system as an experimental platform, this paper proposes two improved static target localization methods based on binocular vision and the traditional localization method: (a) a localization method based on region of interest matching and (b) a localization method based on a pixel coordinate offset. Under the same conditions, the traditional binocular vision localization method and the two improved localization methods are used to locate a spherical target. The experimental results are compared and analysed, and the effectiveness of the improved methods is verified by two performance indicators: the localization accuracy and the localization time efficiency. The experimental results show that to a certain extent, the two improved localization methods can improve the localization efficiency of the vision system and positively affect the performance and flexibility of the astronaut assistant robots.