The docking ring is a typical structure on space targets, and the spatial circle feature extracted from it is an important reference mark for non-cooperative space target vision measurement. However, there are two problems in the pose calculation process: the docking ring pose calculation result of the monocular camera is ambiguous, and the roll angle information cannot be obtained when the pose is solved. In this paper, a non-cooperative space target binocular vision 6- DOF pose measurement method based on docking ring feature is proposed. The binocular vision measurement system is used to solve the ambiguity problem of the docking ring calculation result, and the target coordinate system is constructed by selecting reference feature point outside the docking ring to realize 6-DOF pose measurement. The accuracy and stability of the method are verified by digital simulation experiments, and the results indicate that the method still can calculate stable pose when the pixel position error is 4 pixels. In the scene simulation experiments, the absolute error of vertical optical axis position measurement is less than 1.6 mm, the relative error of parallel optical axis position measurement is less than 0.7%, and the absolute error of attitude measurement is less than 0.2 deg, which can meet the requirements of space navigation mission.