The curves of changes in exothermic mass and exothermic rate of polymer bonded expesive(PBX), polyurethane gum and their contacted system with time during the aging by 100 ℃/20 d were obtained by a microcalorimeter. The samples before and after aging were tested by TG-DSC and FTIR. The results show that HMX based PBX and polyurethane is compatible. After being aged, the surface structures of HMX based PBX show no change, while the partial structures of polyurethane gum undergo degradation. 