Based on the principle of celestial positioning， a stereo positioning method with two observatory satellites was proposed to improve the accuracy of space based detection and positioning. First， according to the performance of the optical camera， the image characteristics of the space target on the optical sensor were analyzed， and the position of the target on the image plane was accurately extracted using the threshold centroid method. Next， based on the coordinate transformation matrix between the target and the observation sensor， the observation vector model was established via the inertial coordinate system. Then， the stereo geometric positioning model of the two observation satellites was established based on the principle of least squares. This model realizes the position transformation of the space target from the two-dimensional image to the three-dimensional space. Finally， the experimental star image capturing the target was generated using ground experiment， and error simulations were performed to verify the positioning algorithm. Simulation results indicate that the positioning precision of the proposed approach can reach 10^-5 m in the absence of errors. When five types of errors， satellite orbit and attitude， camera installation， and centroid extraction， were considered， the positioning error obeyed a normal distribution with a standard deviation of 114.62 m and a mean value of 0， thereby meeting the standard requirements. In this regard， this study provides a novel method for the space based high precision detection and positioning.