Abstract: High-voltage cable is the key power equipment for urban power transmission grids, as well as for the transmission of offshore wind power to the land power grid and the large-scale utilization of renewable energy. However, crosslinked polyethylene insulating material has become the bottleneck for the production of high-voltage cables in China. The entire process for the production and application of high-voltage cable crosslinked polyethylene insulating materials involves multiple steps, multiple structures, and multiple properties. In this paper, four key properties and five basic scientific issues of high-voltage cable used crosslinked polyethylene insulating materials were proposed. The purpose is to promote the research on the basic theory of high-voltage cable crosslinked polyethylene insulating material, as well as to promote the independent research and development of high-voltage cable crosslinked polyethylene insulating materials.