It has been highlighted the importance of huntite/hydromagnesite mineral as an innocent flame retardantmaterial in the plastics in our previous works. In this study, flame retardant behaviors of huntite and hydromagnesite in the polymeric dye coatings were obtained and thesize dependence of this circumstance has been investigated. After getting different size of mineral powders, phase,microstructural and thermal analysiswere undertaken using XRD, SEM-EDS and DTA-TG prior to the fabrication of the composite materials. The minerals with different particle size and content were subsequently added to the polymermatrix (epoxy dye) to produce composite materials.After the fabrication of composites, FTIR analysis has been done and the flame retardant behaviors were evaluated to determine flame retardancy of the coatings. It was concluded that by adding huntite/ hydromagnesite mineral to the polymer matrix, flame retardant epoxy coatings were produced. And it was evident that decreasing the additive size is useful to achieve better flame retardancy.