Hydraulic turbine governing system is an important part of hydropower plants. Generally speaking, a typical hydropower plant is made up of the reservoir, water tunnel, surge tank, penstock, hydraulic turbine, speed governor, generator, and grid. Due to the water inertia, column compressibility and penstock-wall elasticity, the hydro-turbine governing system has a series of significant nonlinear characteristics. For the hydropower plant with long conduits, the elastic water hammer occurrence in penstock can cause major problems to hydraulic turbine. In this book, the sliding mode control for hydraulic turbine governing system based on elastic water hammer is studied.