To effectively reduce the probability of instrumentation and control (I&C) equipment aging failures in nuclear power plants, a preventive replacement aging treatment strategy should be adopted. A single failure–oriented and component aging sensitivity classification model is put forward to classify I&C equipment aging in nuclear power plants, and three methods for assessing I&C equipment life cycles (i.e., aging tests, standards and specifications, and failure data) are provided. Meanwhile, provided with the characteristic curves of I&C equipment aging failures in nuclear power plants, specific aging treatment steps are put forward, including (1) defining the scope of aging treatment in horizontal and longitudinal dimensions of signal flow direction and equipment composition; (2) determining the aging treatment implementation cycle by a life cycle margin setting method; (3) refining the aging treatment implementation process by division of four stages, namely, aged equipment classification, aging data management, aging treatment implementation, and aging testing feedback, to ensure reliable and safe operation of I&C equipment in nuclear power plants.