To study the thermal degradation mechanism of polyether polytriazole (PTPET) and polyether urethane (PET) elastomers, the thermal degradation kinetics, gas phase and condensed phase products of PTPET and PET elastomers were analyzed by thermogravimetric analysis (TG), FTIR (Fourier transform infrared), TG-FTIR combined technology. The results show that the thermal degradation of PET elastomer is divided into two stages. The section from 275-350 ℃ is the first stage, and the section above 350 ℃ is the second stage. The thermal degradation of PTPET elastomer is only one stage, and the initial degradation temperature is 341 ℃. The initial thermal degradation temperature of PTPET elastomer is significantly higher than that of PET elastomer. The change rule of thermal degradation activation energy with the extent of conversion for PET and PTPET elastomers is obtained by a kinetic analysis method. The average value of thermal degradation activation energy of PTPET elastomer is about 290 kJ·mol^-1, and the maximum value of thermal degradation activation energy for PET elastomer is about 150 kJ·mol^-1. The initial thermal degradation of PET elastomers starts with the cleavage of urethane bond. The thermal degradation of the triazole ring of PTPET elastomer starts with the cleavage of the C—N bond, its thermal stability is better than urethane bond.