As a carrier of power transmission in nuclear power plant, the reliability of medium voltage (MV) cable is very important for the safe and stable operation of the unit. Cable defects will lead to cable insulation reduction, cable breakage, equipment trip, and even unit power reduction or reactor shutdown. In this paper, through the analysis of typical cable failure cases, the possible problems in the installation and operation of the cable are studied. Besides, this paper analyzes the common types of defects in MV cables and discusses the causes of these defects. In order to solve these common problems, this paper has proposed a series of management measures, including checking the relevant standard documents of cable installation, preparing the cable installation process improvement plan, modifying the cable installation process, troubleshooting and rectifying the typical problems in cable installation, and strengthening the maintenance and management strategies of MV cables. Through the above measures, the quality of cable management can be effectively improved, the occurrence of cable failure can be reduced, and the overall operation reliability of the nuclear power plant will be promoted. At the same time, these measures also will provide valuable experience for nuclear power projects under construction.