The compatibility of two double-base propellants (SB-1 and SB-2) and priming composition (WX-percussion composition) was studied by differential scanning calorimeter (DSC) and vacuum stability test (VST). The DSC results show that in the mixed systems WX-percussion composition/SB-1 and WX-percussion composition/SB-2,thermal decomposition peak temperatures of WX-percussion composition is increased by 8.8 ℃ and 7.4 ℃, respectively. Then,it can be considered that the two mixture systems are compatible. It is found in VST method that the net increment values of released gases for the two mixture systems are less than 0.6 mL·g-1 and the two systems are judged to be compatible. The peak temperature rise on DSC for WX-percussion composition in the two mixture systems was analyzed and discussed by the “topochemistry” principle,and it is proposed that the processes of thermal decomposition are inhibited by azido nitramine(DA) and nitroglycerine(NG) gases from their evaporation and (or) gasification.