Abstract: Cable, which is regarded as the "blood vessel" and "nerve" of nuclear power plant, is an important electrical setup to ensure the safe operation of the nuclear power system. In this paper, the research progress in cable insulation of nuclear power plants is systematically reviewed. The degradation mechanism of insulation materials in the harsh environments such as strong radiation and high temperature of nuclear power plants is analyzed. The influences of physical and chemical changes caused by irradiation on the mechanical and electrical properties of materials are explored. The modification methods for improving the weather resistance of materials are discussed. It is introduced that the the oxygen barrier effect of nano particles can improve the irradiation resistance of materials. The development of detection and evaluation technologies for nuclear cables is presented. As nondestructive testing, broadband impedance spectroscopy and dielectric spectroscopy are introduced. And the future research directions of nuclear cables are put forward. In the future, the harsh environments such as nuclear radiation, high temperature and LOCA should be further researched, and physical and chemical modification methods should be determined to effectively improve weather resistance, and to develop non-invasive and non-destructive detection and evaluation technologies. The paper provides a reference for the insulation design, production and operation maintenance of cables serving in harsh environment of nuclear power plants.