Hydro-turbine governing system (HTGS) is a nonlinear complex and time variable dynamical system with non-minimum phase parameter. It has an important role in controlling the frequency and power output of hydropower generating units (HGU). Sliding mode control is a resistant control method with state feedback, which the structure will change to achieve optimal performance. In this paper, the sliding mode controller is presented in which the chattering phenomenon of sliding mode using phase control is minimized and the fuzzy logic rules were derived from the sense of  Lyapunov stability theorem to ensure the stability of HTGS system. State equations describing non-linear dynamic modal with additional tank has been expressed and the dynamic behavior of system with different parameters is investigated. The simulation results of three methods PID control, sliding mode control (SMC) and the fuzzy sliding mode control (FSMC) are presented and also in terms of improved performance and stability have been investigated.