The thermal behaviors of CL-20 mixed with three binders ((NC+NG),PET and PBT) at 160-200 ℃ were investigated by NBK LAWA gasometric measuring system. The thermal behaviors were described from the changes of evolved gases and decomposition kinetics. Results show that the apparent activation energies of CL-20 and its mixed systems with (NC+NG),PET and PBT are 176.68，176.31，136.12 and 127.0 kJ·mol-1, respectively. There is less influence of (NC+NG) binder on the decomposition rate and the apparent activation energy of CL-20. The heterogeneous gas/condensed phase reactions between gas products from CL-20 initial decomposition and PET or PBT decrease appear activation energies and increase obviously decomposition rates for CL-20/PET and CL-20/PBT systems. While the mechanism functions of CL-20 decomposition in the three systems are not changed by (NC+NG), PET and PBT.