Abstract: In the process of satellite general assembly, the orientations of the axis of the cameras in the global coordinates of the satellite need to be measured. In this paper, the theodolite is used for that purpose. This paper describes how to define the axis of the camera and measure related angles. The theories and the precision of the technology are analyzed, the optical system of the camera is simplified, a mathematical model of measurement is built, and the precision is analyzed through transfer formulas.