To investigate the intermolecular interactions between insensitive explosive 3, 4-dinitropyrazole (DNP) and high-energy explosive hexaazaisowurtzitane (CL-20), the structure of DNP/CL-20 complex was optimized based on a density functional theory (DFT), six kinds of stable configurations were obtained. The types of intermolecular interaction in complexes were analyzed by natural bond orbital (NBO), electron density topology and reduced density gradient (RDG). The effects of intermolecular interactions on the sensitivity of CL-20 were analyzed from the bond length, bond dissociation energy, bond order of CL-20 trigger bond and the relative charges of nitro group and electron density difference of complex. Results show that the intermolecular hydrogen bond and van der Walls force, including the interactions of N—H…O, C—H…O and N…O, O…O exist in DNP/CL-20 complexes. The analysis of nitro charges and electron density difference show that these intermolecular effects affect the charge distribution and electron density distribution of CL-20 molecules and change the stability of CL-20 trigger bond, resulting in a decrease of its sensitivity. There are good liner relationships among the variations of the bond length, bond dissociation energy, bond order of CL-20 trigger bond and electron density at the bond critical point. The interaction energy of six configurations in the text increases in the order of structure Ⅰ < structure Ⅲ < structure Ⅳ < structure Ⅱ < structure Ⅵ < structure Ⅴ.