Abstract: Polyurethane (PU) boasts outstanding mechanical characteristics, such as robust heat resistance, exceptional impact resilience, and superior fatigue endurance, making it an extensively utilized material in the aerospace and automotive industries, among others. Despite these attributes, PU's practical performance can be compromised by exposure to ultraviolet radiation, moisture, and various chemical agents, which can lead to a deterioration of its physical and chemical properties. In order to investigate the aging effects of various environments on polyurethane (PU) and their impact on mechanical properties, polytetrahydrofuran ether diol (PTMEG)-2,4-toluene diisocyanate (TDI)-2,4-diamino-3,5-dimethylthiophenyl toluene (DMTDA) is selected as the research subject. The study involves measuring the moisture absorption of PU and assessing the changes in its mechanical properties before and after aging under different environmental conditions, such as high temperature(70℃ and 100℃), water immersion, humidity (99℃ ionized water), oil immersion(aviation kerosene), and UV. Furthermore, FTIR analysis is employed to analyze the chemical structural changes of PU before and after aging. This research aims to understand the aging effects of different environments on polyurethane (PU) and their influence on mechanical properties. The results show that the saturation moisture absorption rate of PU after being soaked at room temperature for 168 hours is 1.8%. Compared to the initial PU, the tensile strength and hardness of PU decrease in environments at 70℃ and 100℃, but the tear strength increases. After water immersion treatment, the tensile strength and tear strength of PU decrease by 6% and 3%, respectively, and the hardness decreases by 4.2 HD. However, after humid heat aging, the tensile strength and tear strength of PU decrease by 38.5% and 32.9%, respectively, and the hardness decreases by 22.7 HD. After immersion in aviation kerosene, the tensile strength and tear strength of PU decrease by 13% and 3%, respectively, and the hardness decreases by 3.4 HD. After UV aging, the tensile strength and tear strength of PU decrease by 38.6% and 7%, respectively, and the hardness increases by 4.57 HD. FTIR results indicate that high-temperature environments cause thermal oxidation aging of the ether bonds in PU; humid heat environments cause hydrolysis of the urethane and urea groups in PU; UV environments induce Photo-Fries rearrangement reactions in PU. These changes suggest that PU is susceptible to UV radiation and oxidation.