The invention relates to an infrared-resistant lens preparation method, and the method sequentially forms a first cladding layer, a second cladding layer and a third cladding layer on a substrate in a mode of vacuum evaporation. The substrate is a glass lens or a high molecular material lens. The first cladding layer is a silicon oxide layer, and the second cladding layer is one of a copper cladding film, a gold cladding film, a platinum cladding film and a silver cladding film or the combination of many of the copper cladding film, the gold cladding film, the platinum cladding film and the silver cladding film. The third cladding layer is an aluminium oxide layer. The lens prepared through the above method can achieve 99.5%+/-1% attenuation of infrared light, and has an effect of thermal isolation. The surface of the lens is provided with aluminium oxide, so the lens is resistant to oxidation and wear, is durable, can avoid scratch, is good in practicality, is lower in production cost, and is very high in market popularization value.