Abstract: Thermogravimetry was applied to the study of thermal degradation kinetics and thermo-life of the thermoplastic elastomers (SIS,SBS,SI/BS) in nitrogen atmosphere under different rates of temperature raising (β).The relationship between the rate of temperature-raising and the thermal degradation temperature was determined,and the apparent activation energy and the constant of rate of thermal degradation were found,and the thermo-life equations under different weight-loss rates were obtained.The life of the 3 compounds under different temperatures were calculated.