NOVELTY - Preparing star-shaped net-like bioactive filler comprises adding polyethylene, PVC, polypropylene or acrylonitrile-butadiene-styrene (ABS) resin with polyvinyl alcohol hydrophilic material, then hot melting or hot pressing the materials to obtain sheet-shaped net-like structure, enriching bacteria in sludge source to obtain denitrifying bacteria, crosslinking the denitrifying bacteria with polyvinyl alcohol solution and then adding calcium carbonate to obtain embedded liquid, coating the star-shaped net-like carrier with embedded liquid.    USE - The method is useful for preparing star-shaped net-like bioactive filler material, which is useful for water treatment (all claimed).    ADVANTAGE - The method is capable of preparing the star-shaped net-like bioactive filler material with high denitrifying bacteria concentration, good mass transfer effect, high denitrification efficiency, and good stability.    DETAILED DESCRIPTION - Preparing star-shaped net-like bioactive filler comprises adding polyethylene, PVC, polypropylene or acrylonitrile-butadiene-styrene (ABS) resin with 5-10 wt.% of polyvinyl alcohol hydrophilic material, then hot melting or hot pressing the materials to obtain sheet-shaped net-like structure, enriching bacteria in sludge source from a municipal sewage plant to obtain denitrifying bacteria with a concentration of 108 l/ml to 1010 l/ml, crosslinking the obtained denitrifying bacteria with 80-100 g/l of polyvinyl alcohol solution and then adding 10-40 g/l of calcium carbonate to obtain embedded liquid, uniformly coating the star-shaped net-like carrier with embedded liquid, then adding the coated star-shaped net-like carrier in saturated boric acid solution for 1-3 hours and adjusting the pH value to 8-10, then crosslinking the star-shaped net-like carrier for 3-24 hours, and cleaning the residual surface of the star-shaped net-like carrier. The sheet-shaped net-like structure has length of 0.5-3 cm, width of 0.5-3 cm, diameter of 0.5-2 mm, and square, rhombic, rectangular or circular shaped net hole. An INDEPENDENT CLAIM is included for the star-shaped net-like bioactive filler obtained by the method.