Abstract: Circulating water pump, as an important auxiliary equipment in the power production system,is crucial for the safe and stable operation of thermal power plants. The hydraulic system principle and operation method of butterfly valves at circulating pump outlet are specified, the common faults and solutions on butterfly valves at circulating pump outlet are summed up, and the failed components are gradually analyzed,disassembled, repaired and replaced based on cases, which provides a strong technical experience support for subsequent maintenance activities and improves the operational stability of such components.