Servo Valve Steam Turbine Control System is a key component of the reliability of their work will directly affect the unit's safe and stable operation. In this paper, power generation company Kam 600MW Steam Turbine servo valve hydraulic control system malfunction analysis and line isolation replacement methods and procedures and maintenance considerations. Through the research and detection speed control system servo valve experience, speed control systems found in many of Gu Zhang Ru tone Men swing, and refused to open, reject Guan etc, working conditions in the electro-hydraulic servo valve. Analysis of steam turbine power generation companies Kam servo valve can be closed into the causes of sudden, introduced the company's electro-hydraulic servo valve Kam to a maintenance management experience and methods, other large steam turbine electro-hydraulic servo valve operation and maintenance of a reference.