The invention discloses a high polymer quaternary phosphonium salt antibacterial material and a preparation method thereof. The high polymer quaternary phosphonium salt antibacterial material is prepared by bonding halogenacylhalide type monomers onto macromolecules of an ethylene-vinyl alcohol copolymer (EVOH) through grafting reaction and further performing quaternary phosphonium reaction with trialkylphosphine. The high polymer quaternary phosphonium salt antibacterial material disclosed by the invention has the advantages of broad-spectrum, high-efficient and lasting antibacterial function and good safety, can be shaped and processed into products with the antibacterial function alone, and mixed with polyethylene, polypropylene and other non-polar resin and other types of resin for being shaped and processed into the products with the antibacterial function, and further has broad application prospects. The sterilization efficiency of the high polymer quaternary phosphonium salt antibacterial material prepared by the preparation method disclosed by the invention against escherichia coli, staphylococcus aureus and a variety of bacteria is more than 99%, and the mildew-resistant grade against aspergillus niger, aspergillus terreus and a variety of mildew is 1-0 grade.