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Due to their excellent comprehensive properties, polyurethane materials are widely used in various fields of the national economy and the defense industry. Although polyurethane materials in various forms possess unique and excellent properties, their durability in use remains a concern for everyone. Especially when these polyurethane materials are used in modern weapon systems, changes in their properties can **affect the reliability, safety, and storage lifespan of existing weapons. The aging properties of polyurethane materials are determined not only by their own formulation and manufacturing process, but also by environmental factors such as temperature, humidity, light, oxygen, and water. The main factors causing the aging of polyurethane products are heat, ultraviolet rays, water, and chemical agents. The aging and degradation mechanisms vary under different environmental conditions. Studying its aging properties is complex and difficult. This article provides a review of the aging and degradation of polyurethane materials caused by the factors mentioned above. 1 Photoaging degradation of polyurethanes: The aging and degradation reactions of polyurethane materials induced by light exposure (such as natural light and ultraviolet light) are referred to as the photoaging degradation of polyurethanes. The absorption wavelength of polyurethanes is generally between 290 and 400 nm. Upon absorbing light of a certain wavelength, the molecular bonds in the polymer are broken or the chains cross-link, resulting in the release of CO2, which ultimately leads to a deterioration in the physical properties of the product. At the same time, the chromophoric groups formed during degradation cause the color of the polyurethane to deepen. Generally, under ultraviolet irradiation, polyurethanes have two degradation mechanisms. When polyurethanes absorb light with wavelengths greater than 340 nm, the methylene groups in the isocyanates (such as MDI) are oxidized, resulting in the formation of unstable hydroperoxides. These hydroperoxides further give rise to chromophoric quinone-imide structures, which cause the polyurethane material to turn yellow. Further oxidation leads to the formation of diquinone-imide structures, causing the color to deepen until it eventually becomes amber. The reaction proceeds as follows: when polyurethane materials absorb light with wavelengths between 330 and 340 nm, a photo-fries rearrangement occurs, generating primary aromatic amines; further degradation then produces yellowing products. Another mechanism of ultraviolet degradation in polyurethanes is the breakage of the bonds in the carbamate groups. There are two ways in which bonds can break: one is the breaking of the N–C bond, which results in the formation of an amino radical and an alkyl radical, along with the release of CO2. Another mechanism involves the breakage of the C–O bond, resulting in the formation of a carbamoyl radical and an alkoxy radical; the carbamoyl radical then decomposes into an amino radical and CO2. The breaking of chemical bonds in the molecular chain leads to a decrease in molecular weight, and as a result, the strength of the material also decreases. The photodegradation behavior of castor oil-toluene diisocyanate polyurethane in an artificial aging environment has been studied. The tensile strength of the samples decreased to varying degrees as the duration of ultraviolet irradiation increased; however, with an increase in the amount of ultraviolet absorbers or stabilizers, the retention rate of tensile strength was better accordingly. Studies have shown that the main factors affecting the UV stability of polyurethanes include the soft segments (polyesters, polyethers) and the type of diisocyanate, the mass fraction of the hard segments, the irradiation time, and the sample thickness. Polyester polyurethanes have better UV stability than polyether polyurethanes. Polyurethane elastomers prepared from aliphatic isocyanates exhibit better light stability than those prepared from aromatic isocyanates; the results are shown in Figures 1 and 2.