A novel fused triazolo-pyrimidine energetic compound was synthesized by the two-step diazotization-nitrification method or one-step direct nitration reaction. The physical properties and detonation properties of intermediate 3H-[1,2,3]triazolo[4,5-d]pyrimidine-5,7-diamine (2) and N-(7-oxo-6,7-dihydro-2H-[1,2,3]triazolo[4,5-d]pyrimidin-5-yl)nitramide (3) were further explored. Compound 2 has a higher decomposition temperature (368 °C) than that of 2,4,6-trinitrotoluene (TNT, 295 °C). X-ray crystal-structure analysis shows that the density of compound 3 was 1.97 g cm⁻³ at 100 K. Not only the detonation performance of compound 3 (8845 m s⁻¹, 32.54 GPa) was predicted to approach RDX (8795 m s⁻¹, 34.9 GPa) but displays significantly good safety properties (36 J), which means that compound 3 may serve as a potential high energy insensitivity material (HEIM).