An excellent material for thermal decomposition of ammonium perchlorate (AP) is urgently required. Herein, inspired by natural biopolymer, we prepared CoMn-alginate/AP composite by air atomization method. The results clearly indicated that the bimetallic CoMn-alginate had a 3D network structure consisting of pores and some thin nanosheets. With increasing temperature, the bimetallic CoMn-alginate was decomposed and formed MnCo(2)o(4) nanoparticles by in situ growth. These MnCo2O4 nanoparticles had better catalytic activity for thermal decomposition of AP. In addition, we investigated the effect of using different mass ratios of AP and sodium alginate (SA) and different molar ratios of Co(NO3)(2) and Mn(NO3)(2) on catalytic thermal decomposition of AP. Notably, the thermal decomposition temperature was decreased by 122.9 degrees C. Furthermore, we also proposed a possible synergistic mechanism. All the results indicated that the bimetallic CoMn-alginate had a greater synergistic effect on thermal decomposition of AP.