Abstract: The mechanism of the thermal decomposition of NH₄VO₃ was investigated by TG-DSC in this paper. The analysis results indicate that the decomposition process experiences four steps including the initial three endothermic reactions and a last exothermic reaction. The kinetic parameters of the formation of V₂O₅ were calculated by Kissinger and Kissinger-Crane methods,and the corresponding rate equation was established. The results show that the third chemical reaction is the limiting link during the decomposition of NH₄VO₃,and the activation energy of the reaction is 156.60 kJ/mol,the frequency factor is 2.43 × 10¹⁴min^-1 and the reaction order is 0.94.