Magnesium Hydroxide are magnesium hydroxide produced by chemical synthesis, with high purity and uniform particle size distribution. At the same time, they have excellent flame retardant and smoke suppression functions. They are an excellent choice for manufacturing green halogen-free and environment-friendly flame retardant materials. The thermal decomposition of the product can absorb a large amount of heat on surface of combustor and release a large amount of water to dilute oxygen. The magnesium oxide generated after decomposion is attached to surface of combustor to further isolate the transfer of oxygen and heat, so as to prevent combustion. Compared with aluminum hydroxide, magnesium hydroxide has the advantages of high decomposition and absorption heat, good thermal stability and low relative hardness.