Abstract: Abstract:In the operation of the oil pump No.1 of oil pressure equipment system in the waterturbine generator set No.3 of Huanglongtan Hydropower Plant, the oil pump operated abnormally with large sound, which is serious threat for safe and stable operation of the unit. According to the fault phenomenon, the installation process, the equipment, the skill of the operators and the use of the materials were analyzed, and the oil pump was repaired for eliminating its defects. After the repair, the waterturbine generator set operates safely，the desired result were achieved.

Key words: Keywords:oil pressure equipment, oil pump, oil absorbing barrel, concentricity