Theoretical investigation on the reaction of maleic anhydride (MAH) in the UV radiation cross-linking process of polyethylene as high voltage cable insulation materials is accomplished at B3LYP/6-311 + G(d,p) level. The reaction potential energy information of 10 reaction channels is identified. The results show that the UV radiation cross-linking reaction of polyethylene is initiated by benzophenone, and the multi-functional crosslinker triallyl isocyanurate (TAIC) is needed to take part in the cross-linking process. The behavior of grafting the polar group MAH onto the polyethylene is explored in detail at atomic and molecular levels during UV radiation cross-linking process. The investigation is expected to provide reliable information for optimizing polyethylene UV radiation cross-linking process and for the development of the insulation material of high-voltage cable exceed 500 kV in real applications. (C) 2017 Elsevier Ltd. All rights reserved.