Both of HT-202A and HT-202B, whose major flame retardant elements are N and P, are environment-friendly, halogen-free and intumescent flame retardants, completely compliance with RoHS and REACH regulations. While adding certain amounts to glass-fiber reinforced PBT, the system can achieve UL94 V-0 without migration and precipitation. The system of glass-fiber reinforced PBT which are flame retarded by halogen-free flame retardants(HT-202A or HT-202B) have almost the same mechanical properties but higher anti- tracking performance compared with that of flame retarded by bromine-antimony flame retardants.Generally speaking, the halogen-free flame retardants have many features, for example, halogen-free, environment-friendly, wonderful flame retardancy, cost-effective, excellent water resistance, and are ideal substitutes of bromine-antimony in glass-fiber reinforced PBT.