Abstract: Ultraviolet (UV) warning technology is playing a very important roll in the field of military application. Based on the optimal working waveband of solar-blind UV optical system from 240 nm to 280 nm, an optical system was designed for missile approach warning. To enhance the received light energy, expand the detection range and simplify the system structure, aspheric surfaces and binary elements were adopted in the system. Only five elements were used to realize the focal length 50 mm and field of view (FOV) 43 degrees. iKon-L 936 from ANDOR company was selected as the UV detector, which has pixel size 13.5 m13.5 m and active image area 27.6 mm27.6 mm. After optimization, the maximum RMS radius is only about 11 microns, which is much less than pixel size of the detector and more than 86% of the light energy from each FOV is converged within the circle of radius 6.75 microns. The image quality shows the designed system can meet the working requirements of solar-blind UV optical system. If the focal length can be decreased, the FOV of the system can be enlarged further.