Abstract: CRT digital color printer is a high-technique product developed in recent years, which deals with optics, mechanics, electronics and computer technology. It consists of four main parts, which are called main computer system, optical system, electronic-control system and color printing system. The optical system is a projective optical system with long focus and large field of view,and is an important part of the equipment. The feature, difficulty and result of the design of the optical system are figured out in this paper.