To treat corneal dilatation diseases caused by keratoconus safely and effectively and to reduce manual alignment errors during surgery, an optical system for a corneal cross-linking surgical device was designed in this study. First, based on the requirements of corneal cross-linking surgery related to spot size, uniformity, and working distance, an illumination system was designed based on the principle of uniformation of the compound eye lens array. Second, an infrared lens was designed that was imaged by the human eye with a working distance of 175 mm and a magnification β of -4.2. The aforementioned design was then processed, a prototype of the corneal cross-linking device was built, and the designed optical system was tested experimentally. Experimental results show that the UV illumination light path is 65 mm, output spot diameter is 9 mm, and uniformity is 90.2%, which are comparable to those of similar instruments abroad. The infrared imaging light path can provide clear and quality images for tracking and positioning the human eye during a surgical operation. The optical system of the corneal cross-linking device designed in this study has the characteristics of a simple structure; further, it is low cost, exhibits good performance, and can well meet surgical requirements.