A highly active 1, 2‐bis(trimethylsilyl)diimine(BSD)was synthesized using lithium tris(trimethylsilyl)hydrazine and p‐toluenesulfonylazide as starting materials. 1, 1, 4, 4‐Tetra(trimethylsilyl)tetrazene(TST)was then synthesized further via dimerization reaction of 1, 2‐bis(trimethylsilyl)diimine. The total yield was about 5.0%. The structures of BSD and TST were characterized by means of NMR, FT‐IR, UV‐Vis absorption spectra and element analyses. The mechanism of the dimerization reaction was then studied by quantum chemical calculation method. Results show that BSD firstly is isomerized to 1, 1‐bis (trimethylsilyl)diimine intermediate, and then two 1, 1‐bis(trimethylsilyl)diimine intermediates interact to form TST. Two processes require up to 103.0 kJ·mol^-1 and 114.3 kJ·mol^-1 activation energies, respectively. The theoretical results are consistent with the experimental phenomenon that high temperature condition is favorable for the conversion of BSD to TST.