The development of efficient thermal decomposition of ammonium perchlorate (AP) to improve the combustion behavior of propellants is a vital research topic. In this work, NiMn bimetallic nanoparticles were successfully grown on three-dimensional nitrogen-doped graphene-based frameworks by the chemical co-reduction method. The as-prepared nanocomposite showed a high catalytic activity for the thermal decomposition of AP, which is probably related to the synergistic effect of Ni and Mn. The as-prepared NiMn@3D-NGF nanocomposite was characterized by spectroscopic and microscopic analyses. The catalytic activity of the as-obtained material was investigated by differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA). The high-temperature decomposition of AP was decreased by 115.22 °C and the total heat release from the decomposition of AP increased from 510.40 to 1744.92 Jg⁻¹.