In order to obtain cotton fabrics with high efficiency flame retardance, a new ammonium phosphate type active flame retardant N, N -bis (ammonium phosphate) cysteine (NP-BG), which is nonleaching, covalent attached, durable, functional flame retardants, was synthesized by Mannich reaction and applied to the flame-retardant modification of cotton fabrics. Test results such as FTIR and XPS showed that cotton fabrics had been successfully grafted with NP-BG. The LOI of cotton fabrics treated with 30 % flame retardant was as high as 40.2 %, and aft...