A simple injection molding process was proposed for manufacturing polyethylene (PE) biofilm carrier composited with various powder additives including hydroxyapatite (HAP), starch, bagasse, activated carbon(AC) and magnetic powder(MP) as slow-released nutrients in wastewater biological treatment. The powders were also responsible for improving the hydrophilicity and biomass affinity of the carrier. Pre-attachment between powders and PE particle may achieve great improvement in flow ability of particle-powder mixture during injection molding process. The slow release rate of nutrients (mainly water-soluble starch) from the modified carrier to wastewater can be controlled by the amount of bagasse and activated carbon supplemented in the carrier. The contact angle of a water droplet on the polyethylene surface decreased from 80° to 59° after modification, and the period of biofilm formation on the modified carrier with acclimated sludge reduced from 7 days (on PE carrier without additives) to 4 days. The amount of attached biomass on the modified carrier was also found about twice as that on the common PE carrier. The strength performance test demonstrated the capability of long-term operation for the modified carrier in practical application.