Abstract: The fourth Jiangdu Pumping Station adopts BYKD type hydraulic blade full regulating device,which has caused many problems,such as oil leakage,burning bearing bush and the aging of accumulator skin. The South-to-North Water Diversion Project is under the condition of full load operation with large flow water delivery,and it does not have the conditions for shutdown and maintenance. Therefore,the emergency scheme for depressurization operation is designed to reduce the amount of oil leakage,extend the interval of oil replenishment,and ensure the operation of main engine. In order to solve the problems of complex oil circuit,large amount of pipeline joints,many oil leakage points and burning of bearing bush caused by centralized oil supply mode of external oil supply system. The transformation of built-in blade adjusting mechanism is designed and implemented,the lower piston into the upper one is changed through the comparison and calculation of piston adjusting force,adjusting rod tension and connecting bolt tension,the transformation points are made clear. In this scheme,micro motor,micro gear oil pump and oil cylinder are integrated into the blade adjusting mechanism,which simplifies the structure of the blade adjusting system,makes the oil circuit independent,enhances the sealing performance and improves the reliability of the blade adjusting mechanism.