Tetrazene was analyzed by electric spray ionization mass spectrometry (ESIMS) to study its fragmentation pathways and mechanism. Fragments and structurally informative spectra of tetrazene were obtained. Results show that the atom N is most likely to dissociate in neutral fragment forms of NH₂,HCN,HCN₂,N₃ and N₄,while the fragmentation mechanisms are the cleavage of C—N and N—N and the rearrangment. The relatively stronge peak at m/z 68.9 indicates that tetrazole cycle is stable in the molecule. The presence of stronge peaks at m/z 68.9 and m/z 95.8 suggests that the cleavages of C(5)—N(1) bond and N(2)—N(3) bond are ready to form tetrazole radical,aminoguanidinyl radical and molecular nitrogen.