The invention provides a modified polyethylene microbial carrier filler. Modified polyethylene serves as a main framework material and is subjected to die-cast formation, a hydrophilic polymer coatingis coated on the surface of the framework, and the coating is subjected to high energy electron beam irradiation, so that oxygen-containing polar groups are introduced onto molecular chains of the modified polyethylene to be firmly bound to the modified polyethylene, a hydrophilic surface is formed so as to enhance the hydrophilic property of the carrier filler, and the filler is in a suspended state in water, can turn up and down in the pool and is fully contacted and reacted with the water. According to the carrier filler, every two of a polygonal ring, a first circular ring and a second circular ring are firmly connected by radial ribs, so that the carrier filler is difficult to deform when being used for a long time. Grooves are formed in radial ribs, anaerobes are attached, protection is provided for growth of the anaerobes, dominant population grows, and the biofilm biomass on the carrier is increased.