ABSTRACT The advancement of precision machining technology has heightened safety concerns regarding aluminum (Al) powder explosions in Al product manufacturing. To mitigate this risk, a nitrogen‐phosphorus‐silicon synergistic composite explosion suppressant, MCA@ADP‐MMT, was synthesized via in situ intercalation using montmorillonite (MMT), melamine cyanurate (MCA), and aluminum diethylphosphinate (ADP). The suppression effects of different doses of the suppressant on Al powder explosion overpressure and flame propagation were evaluated through 20 L spherical explosion and Hartmann tube experiments. Based on the thermal properties, SEM‐EDS, and XPS, the heat release kinetics of Al powder oxidation and the chemical composition of its explosion residue were determined. Results show that MCA@ADP‐MMT exhibits superior suppression performance compared to single‐component suppressants. At a 300 wt% addition, it reduced the maximum explosion pressure ( P max ) and the maximum explosion pressure rise rate ( dP/dt max ) by 97.3% and 99.6%, respectively. Additionally, at a mass ratio of 1, it decreased the maximum flame height by 95% and shortened flame propagation time by 75%, effectively extinguishing the flame. Thermal and chemical analyses of explosion products reveal that MCA@ADP‐MMT exhibits both gas‐phase and surface reaction inhibition, significantly increasing the ignition temperature and oxidation activation energy of Al powder, demonstrating superior explosion suppression performance.