Particulate composite systems were investigated by using various fillers such as zeolite, talc, CaCO₃ particles. Various flame retardants were also used to enhance the flammability as well as mechanical propertied in a synergistic manner. We have studied that the effect of particle size on the mechanical properties of composite and the effect of filler on the flammability. The inorganic fillers used in this study were zeolite (average particle diameter = 85.34㎛), CaCO₃(33.93㎛), and Talc(18.51㎛). Heat release rates, ignitability, and mass loss rates were measured by using Cone calorimetry. The flame retardants(DBDPO) and particulate fillers reduce the Maximum Heat Release Rate(M-HRR) in the order of Talc >CaCO₃>Zeolite. As the content of filler increased, tensile strength, flexible strength and elongation decreased but the impact strength increased. In microscopic investigation, the reinforcing inorganic particles seemed to accumulate at the surface of ash layer, and subsequently intercept the oxygen transport and heat transfer into the core area.