Radiation pre-crosslinked polyolefin film and preparation method, and related encapsulation method and encapsulation assembly are provided. The radiation pre-crosslinked polyolefin film for encapsulation is prepared by preparing a film after mixing polyolefin raw materials together; using a radiation energy source to irradiate the film, wherein the radiation energy source directly stimulate a crosslinking reaction of the polyolefin raw materials; adjusting an irradiation dosage of the radiation energy source, such that a crosslinking degree of a pre-crosslinked portion of the film reaches about 3 % to about 95%; and adjusting the irradiation dosage of the radiation energy source, such that the pre-crosslinked portion of the film has a thickness of about 5% to about 100% by a total thickness of the film, wherein: that the pre-crosslinked portion has the thickness of about 100% by the total thickness of the film means the film is all pre-crosslinked.