A novel energetic inner-salt 5, 5′-bis(3-diazo-1, 2, 4-triazole)(BDTZ) was firstly designed and synthesized via two-step reactions of cyclodehydration and diazotization using oxalic acid and aminoguanidinium bicarbonate as starting materials with a total yield of 53.0%, and its structure was characterized by the means of IR spectrum, NMR and elemental analysis. Based on 3LYP/6-311G+(d, p) level, the estimated density of BDTZ is 1.73 g·cm^-3, its detonation velocity is 7780 m·s^-1 and the detonation pressure is 26.72 GPa. The nitrogen content of BDTZ is 74.47%, which contains no toxic heavy metals, showing that BDTZ is a green primary explosive with good detonation performance.