In order to realize the efficient application of TKX-50 in field of solid propellants， the energy performance of poly（glycidylaminopropyl ether） （GAP）-based solid propellants containing TKX-50， CL-20， and TKX-50/CL-20 was calculated using the minimum free energy method， and the feasibility of TKX-50 and CL-20 combination application was analyzed. The application efficiency of TKX-50/CL-20/GAP-based solid propellant was also estimated. The results show that when TKX-50 content increases， balance combustion temperature of propellant in combustion chamber（T_c） and combustion gas average relative molecular mass（） of propellant decrease at the same time， and the theoretical ratio of impulse was first increased and then decreased. The compatibility of TKX-50 and CL-20 was moderate compatibility. It has good thermal stability and safety performance of the TKX-50/CL-20 mixture propellant. It can significantly broaden the choice of the content of each component of the formulation with TKX-50/CL-20 mixture propellant. The lower limit of CL-20 content in the compound propellant with theoretical specific impulse greater than 272 s was only 40% of pure CL-20 propellant. At the same energy level， TKX-50/CL-20 mixture has the characteristics of low cost and low characteristic signal， and has the potential of engineering application.