Axis detection resolution was divided into two sections, the first being the inherent optical resolution of the case and the second the case subdivided accuracy, however, atmospheric channel secondary modulation can directly introduced into detection error, and moreover, influence detection precision. In order to reduce sensitive degree of axis detection system for atmospheric interference, firstly, CCD system and 4QD system as two typical axis detection models were analyzed; the relationship among resolution and inherent optical resolution and subdivided accuracy and beam length was deduced. Afterwards, based on the example of 4QD axis detection system, through the analysis of restricted constraint condition of four-quadrant electro-optical inspection model in atmospheric channel，SNR of distortions and axis offset are two main technical parameters to affect electro-optical inspection system. Finally, the point, subdivided accuracy of axis detection was sensitive to atmospheric interference and inherent optical resolution was little influenced by atmospheric interference. Therefore, changing beam length can improve sensitive degree of axis detection system for atmospheric interference.