Polynitroadamantanes are a class of stable and prospective cage-like energetic compounds. 4-Azido-2,2,6,6-tetranitroadamantane was synthesized from diethyl malonate and paraformaldehyde via cyclization, decarboxylation, formylation, Aldol condensation, O-sulfonylation, azidation, oximation and gem-dinitration reactions with a total yield of 9.8%. The thermal stability of 4-azido-2,2,6,6-tetranitroadamantane was investigated through differential scanning calorimetry (DSC) and thermogravimetry (TG) methods. The onset decomposition temperature and the decomposition peak temperature were located at 219 ℃ and 251 ℃, respectively, indicating a good thermal stability. Compared with 2,2,6,6-tetranitroadamantane and 2,2,4,4,6,6-hexanitroadamantane, the replacement of hydrogen in C-4 by azido group resulted in decreased thermal stability, in contrast, the thermal stability was improved by replacing the gem-dinitro group in C-4 by azido group. By using desity functional theory, 4-azido-2,2,6,6-tetranitroadamantane showed a density of 1.79 g·cm^-3, a detonation velocity of 7770 m·s^-1, and a detonation pressure of 26.68 GPa. Results indicate that 4-azido-2,2,6,6-tetranitroadamantane is a high-energy compound.