Abstract: Based on a small-sized projector with 4k resolution, an easy processing fisheye lens with low cost, small diameter and high resolution was designed. Through rational selection of structure, focal power distribution, aperture position setting, lens shape adjustment, materials optimization and match, the image aberration was fully corrected. The lens only consist of nine glasses, with the field angle of 175°, F^# of 2.2, back focal length of 39.8 mm. At the Nyquist frequency of 131 lp/mm, the MTF of 1.0 field is 0.3, the MTF of other fields are all above 0.43. All the technique parameters meet the requirements of using the projector. The Monte Carlo analysis results show that all the tolerance is in the normal range that is feasible to process, hence the lens is fit for batch production and assembly.