Abstract: Maleic anhydride grafted polyethylenes were prepared by UV light irradiation and characterized by FTIR.The result showed that MAH had successfully grafted onto HDPE,LDPE and LLDPE.LLDPE and LDPE presented higher grafting level than HDPE at the same condition.The effects of UV irradiation time, monomer (MAH) and initiator (BP) concentration on grafting rate and gel content of grafted polyethenes were studied.Grafting reaction of MAH onto polyethylenes proceeded quickly,and the optimal duration of UV irradiation is 30 s.BP concentration was an important factor effecting on the grafting rate and gel con- tent,high concentration of BP could cause more severe degrading or cross-linking reactions,so the optimal concentration of BP was 0.2wt%.The grafting rate increased with the increasing of MAH concentration.