Abstract: For better testing and calibrating the space-used telescope, a novel calculating model was introduced to simulate tracing process of the satellite. The coordinate transform theory was used for the indoor rotating target, the result was coincident with the spherical trigonometry. A model was deduced to illustrate the relationship between the tracing errors and the position errors of detecting system and the telescope gyration centre. The result showed that, a position error of 0.2 m in the vertical axis direction simply causing a constant elevation angle tracing error of 5.658 74, without any influence on other tracing performance. An error of 0.002 m in the horizontal axis direction caused coupling tracing errors both in azimuth and elevation measurements, the azimuth angle tracing error ranged between 0.056 78~0.139 25, azimuth angular velocity error was 0.007 01 per second, the azimuth angular acceleration error was 0.002 56 degree per second square, while the elevation angle tracing error was about 10-4 order of magnitude, and the angular velocity and angular acceleration was about 10-6 order of magnitude. The tracing performance was independent of position error in the collimation axis direction. This conclusion provides reference for testing and assembling space-used telescope.