Co-crystal technology is one of the effective methods to reduce the sensitivity of CL-20. Studying the chemical reaction of CL-20 co-crystal under shock is helpful to understand the shock reaction mechanism of CL-20 co-crystal， which is of great significance to the safety evaluation and analysis of explosives. In this study， the molecular dynamics method of ReaxFF-lg reaction force field and the non-equilibrium loading method were used to simulate the shock compression process of CL-20/DNT， CL-20/DNB and CL-20/MDNT co-crystals at 2-5 km·s^-1 shock velocity. The thermodynamic evolution characteristics， initial chemical reaction path and product information of energetic co-crystals after shock are obtained and compared with those of CL-20. It’s discovered that the three co-crystals of CL-20/DNT， CL-20/DNB and CL-20/MDNT have a certain degree of shock sensitivity reduction， and the order of shock sensitivity of the three co-crystals is CL-20/MDNT>CL-20/DNB>CL-20/DNT. The decomposition reaction of the three co-crystals all starts from the decomposition of CL-20， and the decomposition rate of CL-20 is faster than that of DNT， DNB and MDNT. At the shock velocity of 2 km·s^-1， the polymerization reaction of CL-20 co-crystal occurs first. The polymerization reaction between CL-20 and co-crystal ligand molecules is earlier than that between CL-20 molecules， and the reaction frequency is much higher than that between CL-20 molecules. At the shock velocity of 3 km·s^-1， the N─N and C─N bonds of CL-20 are first broken， and the cage structure is destroyed. At the same time， NO₂ is generated. NO₂ generated by the initial bond breaking of CL-20 further combines with the eutectic ligand molecules DNT， DNB and MDNT to reduce the concentration of the intermediate products of CL-20 reaction， so as to achieve the desensitization effect. At the shock velocity of 4 or 5 km·s^-1， the ring skeleton structure in CL-20 is directly destroyed， the C-N bond is broken， generating small molecular fragments， including N_2， NO₂， H₂， CO₂， H₂O and other products.