In order to clarify the influence mechanism of H₂O and H₂O₂ molecules on the thermal stability of energetic cocrystals， molecular dynamics （MD） simulation method was employed to analyze the diffusion behavior and thermal decomposition mechanism of solvent molecules in α-CL-20 and CL-20/H₂O₂ （orthogonal/monoclinic）. The results show that both H₂O and H₂O₂ will diffuse out of the cell as the temperature rises， among which H₂O molecules diffuse faster； when the temperature is lower than 500 K， the monoclinic CL-20/H₂O₂ lattice framework has the ability to hinder the diffusion of H₂O₂ molecules. When the temperature rises above 500 K， this hindering effect no longer exists. In the process of thermal decomposition， α-CL-20 releases energy the slowest， and the decomposition of CL-20 also proceeds the slowest； when the temperature is lower than 1500 K， the solvent exhibits a certain stabilizing effect on the thermal decomposition of energetic components， but this effect disappears as the temperature rises. In addition， the presence of solvents can increase the lattice energy significantly.