4, 4′, 5, 5′-Tetranitro-2, 2′-biimidazole (TNBI) was synthesized using ammonium acetate and glyoxal as starting materials by the reactions of cyclic condensation and nitration. A series of 4, 4′, 5, 5′-tetranitro-2, 2′-biimidazolate energetic ion salts were prepared with the cations as 3, 4-diaminofurazan (DAFTNBI), oxalyl dihydrazide (ODTNBI), 3, 6-dihydrazino-1, 2, 4, 5-tetrazine (HTTNBI), biguanide (DBGTNBI), gunanyl urea (DGUTNBI), 4-amino-1, 2, 4-triazole (DATTNBI), urea (DUTNBI). The structures of all compounds were confirmed by IR, ¹H NMR, ¹³C NMR and elemental analysis. The single crystal of TNBI·H₂O was obtained in the water system.The crystal of TNBI·H₂O belongs to monoclinic system, space group P2(1)/n, cell parameters: a=0.5051(17) nm, b＝0.8528(3) nm, c=1.5270(5) nm, β=96.948(6)°, V＝0.6529(4) nm³, Z＝4, D_c＝1.781 g·cm^-3. The thermal properties of seven energetic ion salts were studied by differential scanning calorimetry (DSC) and thermogravimetric (TG). Results show that the thermal decomposition peaks of these energetic ionic salt are at 199.23, 204.52, 230.13, 266.96, 240.63, 187.98 ℃ and 260.19 ℃, respectively, which indicates that their thermal stability is good.