Abstract: In order to study the nonlinear dynamical behavior of hydro-turbine governing system,a new dynamical model for the hydro-turbine governing system with elastic water hammer-impact and the second order model of generator was established,which is based on the model of simple surge shaft.By virtue of bifurcation diagram,Poincare maps,the power spectrum diagram,the time domain diagram,the orbits diagram and the spectrum diagram,the nonlinear dynamical responses of generator’s relative deviation of rotational seed and the water pressure at the entrance of surge shaft were analyzed.Through the analysis,the adjustable range of the speed governor that ensure governing systems stable operation were got.The results provide important simulation reference for the safety operation of hydro-turbine system.