Flame retardant yarn is a kind of special fabric that can retard flame combustion. It is mainly used in the production of protective clothing, special function clothing, industrial fabrics, and is widely used in fire protection, oil, electricity, natural gas, metallurgy, machinery, mining, chemical industry, coal, shipping and other industries. Flame retardant yarn has low fire point, good flame retardant effect and is not easy to ignite. It can extinguish fire from fire source and has waterproof function to achieve flame retardant effect. Compared with non flame retardant yarn, there will be obvious difference in fire.