The invention belongs to the technical field of 3D (Three Dimensional) printing and provides a polyethylene powder material for 3D (Three Dimensional) printing and a low-cost preparation method thereof. The method comprises the following steps: mixing dicalcium phosphate powder, waste egg shells and polyethylene powder and carrying out ball milling; carrying out microwave heating and reacting to generate porous hydroxyapatite microspheres; meanwhile, melting polyethylene and permeating the polyethylene into pores of the microspheres to form tight embedding combination; then impacting and polishing through a fluidized bed to obtain the polyethylene powder material for the 3D printing, which has extremely high sphericity degree. Compared with a traditional method, the prepared polyethylene powder material has the advantages of small grain diameter, good sphericity, high melting flowability and good processing performance; products with high precision, small roughness and excellent performance are conveniently rapidly and efficiently prepared in a 3D printing process and a whole preparation technology is simple and easy to manipulate; the method also has the advantages of easiness forobtaining raw materials, low energy consumption, low preparation cost and capability of realizing large-scale popularization and production.