This paper first introduces the basic knowledge of DFT and spectrum analysis, introduces the "fence" effect and the computation of FFT analysis, understanding the FFT algorithm in MATLAB. This paper reviewed the commonly used method to estimate the frequency, including the maximum quasi likelihood algorithm, Rife algorithm and modified Rife, the MUSIC algorithm. This paper finally put forward with the ratio of discrete spectrum correction method to estimate signal frequency amplitude and phase Angle, the computer simulation analysis with MATLAB, use ratio correction method estimate signal frequency amplitude and phase of its high precision, small error, implementation is simple and convenient. This paper first introduces the basic knowledge of DFT and spectrum analysis, introduces the "fence" effect and the computation of FFT analysis, understanding the FFT algorithm in MATLAB. This paper reviewed the commonly used method to estimate the frequency, including the maximum quasi likelihood algorithm, Rife algorithm and modified Rife, the MUSIC algorithm. This paper finally put forward with the ratio of discrete spectrum correction method to estimate signal frequency amplitude and phase Angle, the computer simulation analysis with MATLAB, use ratio correction method estimate signal frequency amplitude and phase of its high precision, small error, implementation is simple and convenient.