Flame retardant masterbatch is a widely used additive product that can prevent plastic ignition and inhibit flame propagation. When the flame retardant masterbatch is added to the plastic, the decomposition of the flame retardant produces a heavier nonflammable gas or a high boiling point liquid, which covers the plastic surface and insulates the diffusion of oxygen and combustibles, through the decomposition or sublimation of the flame retardant, the temperature of the plastic surface is reduced, the flame retardant captures the active radicals and interrupts the chain-type oxidation reaction.