Abstract: With the continuous operation of nuclear reactor, primary equipment and components such as internal components of the reactor gradually aging, and the reliability of key important equipment decreases, so it is necessary to replace or repair the relevant parts of the equipment. Due to the particularity of nuclear technology, once the reactor is activated, the equipment of the reactor internal components is highly radioactive, and special maintenance strategies and tools must be used for maintenance treatment. In this paper, combining with the pressurized water reactor nuclear power plant maintenance site, through systematic and comprehensive risk analysis for high radioactive environment maintenance strategy, special tools for underwater long-distance operation were designed and manufactured, which was successfully applied to the nuclear power maintenance site. The successful removal of the flow by-pass plate of the reactor component verifies the rationality of this maintenance strategy and the reliability of the special tools for underwater long-distance operation, which provides experience and reference for the maintenance technology of nuclear power plant in high radioactive environment.