A binary gradation model of polystyrene foam particles and glass beads was constructed， and the optimal particle size gradation of polystyrene foam particles and glass beads was about 5∶2 and the volume ratio was about 100∶7. Based on the gradation model， the aggregate was prepared and the composite fire-resistant polystyrene foam boards were fabricated using molding process. The microstructure diagrams revealed that the aggregate stacked up in a dense and well-organized arrangement. An analysis was conducted to investigate the influence of silicate cementitious material， SiO₂ aerogel， and hydrophobic agent on the performance of the composite fire-resistant polystyrene foam board. The results indicate that an increase in the content of silicate cementitious material enhances the fire resistance and tensile strength of the composite fire-resistant polystyrene foam board. Conversely， an increase in SiO₂ aerogel content results in a reduction of thermal conductivity and tensile strength， accompanied by an increase in the softening coefficient. Additionally， the water absorption rate decreases with an increase in the content of the hydrophobic agent.