Power system stabilizer (PSS) is one of the most effective measures to damp the power system low frequency oscillation, the entire parameter estimation is generally more complex and difficult. According to the measured generating set uncompensated phase frequency characteristics, this paper use the objective function which is minimizing the sum of the absolute value to design PSS parameters, and the absolute value is composed of the difference between the square of required compensation phase in excitation system and the square of phase provided by PSS. Accordingly, this paper puts forward a kind of PSS parameter design method based on genetic simulated annealing algorithm. The parameter design method is applied to a hydroelectric power station generator No. 1 of China South power grid and then the results of the simulation show that using PSS parameter design method based on genetic simulated annealing algorithm can effectively damp the power system low frequency oscillation, and at the same time, simulation results verify the accuracy and validity of the method.