An antibacterial plastic was prepared with the quaternary phosphonium salts grafted low density polyethylene by reactive extrusion.The tributyl-3-[(and 4-)vinyl benzyl] phosphonium chloride was synthetized with 3-(and 4-)chloromethylstyrene and tributylphosphine before the extrusion.The dependence of antibacterial properties on the content of the quarter phosphonium salt for E.coli and S.aureus were investigated.