To alignment the posture between the camera and the star-sensor on the GF-2 satellite， a high precision automatic measurement system was established. For the measuring system， a high precision measurement algorithm based on multi-sensor fusion， an automatic measurement plane based on design data， and a cube mirror normal measurement method based on geometric figure recognition were investigated. The system was mainly constituted by a double column guideway system， a precision turntable， and an autocollimation theodolite assisted with CCD camera. The instrument posture was calculated by fusing the data of the pitch angle and the horizontal angle of the theodolite and the rotation angle of the turntable. In measurement， the system was fixed and calibrated， and an automatic measurement plan was generated firstly. Then the theodolite was driven to the desired location and desired angle. If there was no collimated light from the mirror to the theodolite， the CCD camera would search the cube mirror and calculate the deviationt of the theodolite. Then the location and angles of the theodolite were adjusted and the posture of the cube mirror of the instrument was measured. Experimental results indicate that the precision of the system is within 5″and the maximum deviation compared to the standard value is 4.1″. The system has been used in the assembly of GF-2 satellite， its maximum measuring standard deviation is 3.5″， and satisfies the system requirements for higher precisions and rapid speeds.