Simultaneous improvement of the safety performance and thermal decomposition properties of ammonium perchlorate (AP) remains a significant challenge. Therefore, based on inspiration from biological materials, we have prepared a novel copper alginate/ammonium perchlorate (Cu-alginate/AP) composite by facile air atomization. The evaluation of the safety performance and thermal decomposition indicates that these properties were significantly improved. In addition, the possible catalytic mechanism of thermal decomposition of AP is proposed herein. It should be noted that Cu-alginate is a three-dimensional network structure and was uniformly coated on the surface and inside of the AP. When the composite is stimulated by external forces, this unique structure plays a buffering role, absorbing energy and greatly improving safety performance. With increasing temperature, the Cu-alginate easily decomposed and renascent Cu-based nanoparticles were generated by in situ growth. These renascent nanoparticles exhibited excellent catalytic activity for the thermal decomposition of AP. As expected, the bio-inspired material can smartly improve both the safety performance and thermal decomposition of AP. Therefore, these findings provide a promising strategy for the development of composite solid propellants.