Abstract: The processes of thermal decomposition of HTPB are studied using thermal analysis method and infrared spectroscopy.The products from thermal splitting decomposition of HTPB are analysed by gas chromatography.The experimental results show that the whole courses of the thermal decomposition of HTPB can be divided into two stages.The former is related to the degradation and cross-linking of the weak-link bonds of the polymer,and the latter is considered to be the degradation caused by the breakage of the main chain of the polymer.The mechanism of thermal decomposition of HTPB proposed may elimi-nate the divergence of previous statements.