Energetic cocrystals are an attractive new family of explosives with a potential for high energy and low sensitivity. The practical application of cocrystal explosives highly requires in-depth understanding of their thermal kinetic behavior, but the relevant research is still rare. In this study, we selected CL-20/BTF (2,4,6,8,10,12-hexanitrohexaazaisowurtzitane/benzotrifuroxan) cocrystal as a typical cocrystal explosive to investigate its thermal kinetics and decomposition mechanism. The thermal behavior of CL-20/BTF shows no phase transition or solid–liquid melting process before decomposition, which is distinct from those of pure CL-20 and BTF crystals. Further, we identified the thermal decomposition of CL-20/BTF as a particular reaction kinetics consisting of two parallel autocatalytic paths, in which the contribution of these two paths to the overall reaction varies with the change of heating rate. Based on the established kinetic model, important thermal safety indicators including TMRad and SADT are simulated. Finally, in situ infrared spectroscopy was performed to detect the molecular evolution of CL-20/BTF cocrystal during thermal decomposition, which is helpful to understand the origin of its thermal kinetics. It is found that the unique decomposition mechanism of strong intermolecular coupling between CL-20 and BTF molecules is responsible for the parallel reaction paths of the thermal kinetics of the CL-20/BTF cocrystal.