Using 4，5-dicyano-2-aminoimidazole as raw material， 4，5-Bis-（chloro-dinitro-methyl）-2-diazoimidazole was prepared through three-step reactions of oximation， chlorination， diazotization. The structure was characterized by X-ray single crystal diffraction analysis， Fourier transform infrared spectroscopy（FT-IR）， nuclear magnetic resonance spectroscopy （1H NMR， 13C NMR） and high resolution mass spectrometry（HRMS）. The thermal properties were studied by differential scanning calorimeter and thermogravimetric analyzer. Its structure was optimized using Gaussian09 and its performance was estimated using Explo5 v6.01.. The results show that the crystal of 4，5-Bis-（chloro-dinitro-methyl）-2-diazoimidazole belongs to the triclinic P1 space group. The unit cell parameters are a=6.6196 （10） Å， b=8.1685（13） Å， c=13.0272（19） Å， V=666.96（18） Å， α=100.166（4）°，β=102.560（4）°， γ=97.153（5）°， Z=2， F（000）=368； D_c=1.848 g·cm^-3. Its thermal decomposition temperature is 122.14 ℃.The theoretical detonation velocity is 8574 m·s^-1 and the theoretical detonation pressure is 32.8 GPa. According to the BAM standard method， the impact sensitivity is 4 J and the friction sensitivity is 100 N.