The present study suggests that the thermal decomposition of 5-nitro-1-hydrogen-tetrazole might be the main contribution to the N 2 releasing process of 5-nitro-tetrazole's decomposition. Three reaction channels of 5-nitro-1-hydrogen-tetrazole were revealed in ab initio molecular dynamics (MD) simulations. The direct ring rupture of N1–N2 bond breaking has the lowest energy barrier at the first reaction step and is expected to dominate the thermal decomposition. Hydrogen-transfer leading process has a relatively higher energy barrier for the first step. However, the proton-transfer rate could increase dramatically due to the quantum tunneling effect. The direct ring-opening reaction through the C5–N4 bond breaking is less important for its very high activation energy.