The optical design of fish-eye lens used for monitoring is discussed. First, based on the system requirment, the equidistance mapping mode in which the directional information of object can be deduced directly from image is selected, then the full frames imaging form is chose for it′s relative longer focal length, which can satisfy the resolution demands of system. Through arranging the configuration and choosing materials rationally, the abberations of system are corrected efficiently. And the drop-off of illumination at the full field of view is alleviated by increasing the pupil coma intentiaonally. Finally a wide spectral fish-eye lens is presented, whose operating wavelength range is from 486 nm to 900 nm, field of view is 180°, and F number is 2.8. The design results demonstrate that the MTF at Nyquist frequency 63 lp/mm is higher than 0.3, the illuminance at the edge field of view is higher than 50% of central field of view, and the f-theta distortion is less than 3%. All indexes satisfy the commands of system.