Telescope guiding error caused by atmospheric turbulence is discussed, which affects significantly the accuracy of telescope auto-guiding system. Guiding precision of a single point source target is limited by the atmospheric coherent length and coherent time, and several point source targets and extended celestial bodies guiding precision also have relation to the turbulence height. Furthermore, analysis and simulation (numerical simulation) results show that modern astronomical observations must consider the influence of atmospheric turbulence on the accuracy of the auto-guiding system. Extending the exposure time can reduce the influence of the turbulent atmosphere, but also reduce the feedback control frequency of the auto-guiding system. The guiding beacon of several stars or extended source can reduce partly auto-guiding error caused by high-layer atmospheric turbulence, which can appropriately reduce the exposure time of the auto-guiding system, and improve its feedback control frequency.