Dynamic linear-motion-target generator is used to detect or calibrate performance indexes such as dynamic resolution or tracking bandwidth of electro-optical tracking and pointing system. A collimator is placed inside the dynamic target generator to simulate the infinite dynamic target, motion graphics are placed at the focal plane of thecollimatorand moves in a variable speed linear motion to simulatethe movement dynamics of the ground scene. Due to the characteristics of long focal length, large aperture and large field of view of the generator's collimator, the secondary spectrum of the collimator needs to be considered, based ontheory ofchromatic aberration eliminationthe secondary spectrum is corrected and other aberrations such as field curvature are balanced. An optical collimating systemwith focal length of 1 m and field of view angle of 5° is designed.The design results show that the MTF is better than 0.3@100lp/mm,the distortion is 0.03%, and axial chromatic aberrationis much less than the focal depth, which effectively corrects secondary spectrum. The on-axis and off-axis spatial resolution of the optical systemis detected by the resolution plate method, the detection results show thatspatial resolution of the collimatorreaches 152lp/mm, which meets the requirements of the system.