In order to study the thermal decomposition behavior of 2, 2-azobi [4, 5-bis (tetrazole-5-yl)]-1,2, 3-triazole (NL24), the structural morphology and thermal decomposition characteristics of NL24 were studied by means of scanning electron microscopy, thermogravimetric analyzer, differential scanning calorimeter and thermogravimetric infrared mass spectrometry. Kinetic parameters such as apparent activation energy and exponential pre-factor were calculated by Kissinger, Ozawa and boheme estak, and finally the thermal decomposition mechanism of NL24 was deduced. The results show that NL24 has two main weight loss stages at the temperature rate of 10 ℃·min-1. The first weight loss stage occurs at about 180 ℃, which belongs to the dimethyl sulfoxide volatilization heat absorption process, and the thermal decomposition of NL24 occurs at the second weight loss stage, which is between 270 ℃ and 300 ℃. The violent decomposition of NL24 not only produces gas quickly, but also belongs to autocatalytic reaction. The main gases are N2, HCN, HN3, etc. The apparent activation energy and pre-exponential factor of the decomposition process are 174.69 kJ·mol-1 and 1016.60 s-1, respectively. The reaction model of the thermal decomposition stage of NL24 is random nucleation and subsequent growth.