The invention relates to a
polyethylene-
polystyrene resin and a preparation method thereof. The preparation method comprises the following steps of: performing pre-
irradiation treatment on
polyethylene resin by using beta rays or gamma rays; adding the
polyethylene resin after the pre-
irradiation treatment, a dispersing agent, a
functional monomer, an emulsifying agent, a nucleating agent and a homopolymerization inhibiting agent into a reactor to perform suspension graft
polymerization reaction for a certain period of time at a certain temperature; and filtering, washing and
drying a suspension graft product to obtain the polyethylene-
polystyrene resin. The concentrations of macromolecular peroxides generated by the pre-
irradiation are distributed evenly, so side reactions such as
monomer homopolymerization,
polymer crosslinking and / or degradation and the like caused by a micromolecule chemical initiator are avoided; the percent
grafting ratio reaches 21 to 42 percent; the homopolymerization inhibiting agent reduces the homopolymerization of the
monomer in the suspension
grafting process; and the polyethylene-
polystyrene resin has the tensile strength of more than 22 MPa, breaking elongation of over 90 percent and
elastic modulus of more than 480 MPa, and has good mechanical properties such as strength, tenacity,
impact strength and the like.