Tris(4-bromophenyl) phosphate(BPP). bits(4-bromophenyl) sodium phosphate(BSP) and 4-bromo-phenyl disodium phosphate(BDP) were synthesized by interracial reaction. Flammability of PET fabrics treated with these three synthesized flame retardant was investigated through LOI measurement and times of flame contact. LOI increased with the increase of content of BPP BSP and BDP in fabrics and satisfactory flame retardancy. LOI 28, could be obtained at 3~4% of add-on.