Abstract: The low frequency oscillation has great impact on the operation of large scale interconnected power system,and the Power System Stabilizer（PSS） is widely applied to inhibit the low frequency oscillation under negative damping.However,how to deploy PSS in multi-machine power system to stabilize low frequency oscillation is the urgent problem to be solved.In this paper,two kinds of PSS deployment methods,the participation factor method and the eigenvalue sensitivity method are discussed.The state matrix of the system is obtained by applying eigenvalue analysis,based on which the participation factors and the partial derivatives of the state matrix to any parameters are computed.Through the analysis and comparison of both methods,their advantages and disadvantages and application scope are pointed out.In the end,the benchmark two-area four-machine system is taken as example to get the participation factors and sensitivity of interested low frequency oscillation.The results testify the accuracy of the dominant machine judgment for specified low-frequency oscillation mode by using of both methods,and the affecting factors are analyzed and discussed.