Flame retardation of PET fabric was carried out via UV curing of three phosphate-containing methacrylates and ammonium polyphosphate(APP). Add-on and add-on efficiency increased with increasing functionality of the methacrylates where the photopolymerization occurred on the PET fabric rather than inside of fabric. The APP addition increased the flame retardancy with slight decrease in fixation. The Flame retardancy up to a LOI of 25.9 was achieved by the UV coating of MMEP alone. The UV coating of MMEP with 25%(owm) of APP addition showed the highest LOI value of 28.5 which is durable to five laundering cycles. The obtained flame retardancy of UV-coated PET fabrics with the phosphorous-containing methacrylates may result from a condensed phase mechanism as indicated by lowered thermal decomposition temperatures, higher carbonaceous char content with higher residue number, which reduces the generation of flammable materials by changing the pyrolysis path of PET.