Disclosed in present invention are a high-wettability separator and a preparation method therefor. The separator comprises an ethylene copolymer, a grafting polyolefin, an ultrahigh molecular weight polyethylene having a molecular weight ranging from 1.0×106 to 10.0×106, and a high-density polyethylene having a density ranging from 0.940 g/cm3 to 0.976 g/cm3, the content of the ethylene copolymer is 1-5 parts by weight, and the content of the grafting polyolefin is 0-5 parts by weight, on the basis that the total weight of the ultrahigh molecular weight polyethylene and the high-density polyethylene is 100 parts. The separator has a contact angle with lithium ion battery electrolyte of 20° to 40°.