Through the analysis of imaging principle， simulation of optical model and construction of the principle prototype， the main factors affecting the calibration accuracy of the autocollimation calibration system in the experimental environment are discussed， and the main issues of the calibration system are put forward， which should be noticed in the design and work， including pixel size selection， image point location algorithm， focus amount calculation and system installation error. According to the analysis results， the calibration error of the principle prototype is corrected. Finally， the calibration accuracy of the principle prototype is less than 0.4 mm， and the calibration accuracy of the rotation in X， Y and Z directions are less than 0.6"， 0.6" and 12" respectively. The relative error of accuracy is better than 0.2%.