5,5′-Bis(2,4,6-trinitrophenyl)-2,2′-bi(1,3,4-oxadiazole) (TKX-55), a thermally stable explosive, was synthesized with a total yield of 60.3% from trinitrotoluene via oxidation, chlorination, substitution and cyclization reactions. The chemical structure of TKX-55 was characterized by infrared (IR) spectroscopy, nuclear magnetic resonance (NMR,¹H and ¹³C). Next, we optimized the chlorine and substitution reaction conditions.When SOCl₂ acted as chlorine reagent, the highest yield was up to 88.8%. When THF was used as solvent and the reaction time was 24 h, NaHCO₃ was a better acid-binding agent compared with others (such as NaOH、Et₃N and Na₂CO₃). The decomposition temperature of TKX-55 is 335 ℃. After optimizing the molecularstructure of TKX-55, its detonation velocity (D=8052 m·s^-1) and detonation pressure (p=28.6 GPa) are calculated by Kamlet-Jacob formula, which are better than those of PYX (D=7590 m·s^-1, p=26.2 GPa) and HNS (D=7545 m·s^-1, p=23.6 GPa).