Through choosing panoramic annular lens model and using CODE-V,a new small infrared panoramic lens with compact structure is completed. The result indicates that panoramic annular lens model is conducive to miniaturization and integration of the lens,and the difficulty of lens′s processing is reduced by setting the model′s two transmission surfaces and two reflection surfaces to sphere,and the optimizing of the relative aperture can improve system′s sensitivity and resolution. The system aberrations are effectively balanced by setting asphere and the diffraction surface in relay system. The lens has a waveband 3-5 μm,a field of view ±55°-±100°,F-number of 1.3,effective focal length of -0.53 mm,overall length of 64.5 mm,and the resolution limit of the lens is only 6.3 μm. The analysis of the CODE-V software demonstrats that the lateral aberration of the system is between -0.021-0.021 mm,only 1.6 times the diameter of the Airy spot,and the value of the modulation transfer function (MTF) is greater than 0.2 at 40 lp/mm,and the lens has a good imaging quality.