In order to improve the reliability of the product, an optical passive non-thermal infrared lens working in the 8--14 m waveband is designed, which can image clearly in a wide temperature range without focusing. The system selects a new type of chalcogenide glass that can be processed by pressing and is suitable for mass production. The optical lens adopts three-piece structure. It is a passive non-thermal lens which is based on the principle of refraction/diffraction.The focal length of the system is 42 mm and the F-number is 0.9. The lens matches an uncooled long-wave infrared detector with pixel size of 14 m and pixel number of 640×512. The lens can clearly image in the temperature range of -40 ℃--50 ℃ and in the full field-of-view. The modulation transfer function(MTF)is greater than 0.38@36 lp/mm at the operating temperature in the full field-of-view, which is close to the diffraction limit.