The polyethylene is widely used for electrical cable insulation in power cables. This material is prone to develop an inevitable effect of electrical and chemical degradation after some long-standing operation. Due to the physical and engineering importance of this phenomenon, significant effort has gone into tackling this problem, using approaches relevant to the interference of ageing mechanism, to space charge measurement and to the identification of the chemical nature of traps. The aspect on space charge phenomena has been extensively analyzed recently. The occurrence of space charge within these polymeric materials and subsequently electroluminance would introduce an early ageing effect. To assist the space charge analysis, various space charge profiling and measuring tools have been developed recently, such as PEA (Pulsed Electro-Acoustic) method. Electroluminance has been studied under both dc and ac fields. In addition, the research area on this topic has gradually extended to the numerical-computational technique of analyzing the space charge dynamics via simulation based on various space charge models.