提出了许多改善ＦＦＴ离散谱估计精度的方法，但必需知道谱峰的大体范围。作者证明了对称窗函数的频谱主瓣内的两条ＦＦＴ谱线为最大和次大。根据这一性质，对多频率信号，可按照ＦＦＴ谱线局部极大的原则确定真实谱峰位置，这是非常简便且易于编程的准则。仿真结果表明，如果两个真实谱峰相距不少于三条谱线，上述准则是正确的；随着谱峰接近，则可能存在误判，并且加汉宁窗错误率低于矩形窗。 Many methods to improve the accuracy of FFT discrete spectrum estimation are proposed, but the general scope of spectral peaks must be known. The authors show that the two FFT lines in the main lobe of the spectrum of the symmetric window function are largest and second largest. According to this property, the true spectral peak position can be determined according to the principle of local maximum of the FFT spectrum for multi-frequency signals, which is a very simple and easy-to-process criterion. The simulation results show that the above criterion is correct if the two real spectral peaks are separated by no less than three spectral lines, and may be misjudged as the spectral peaks approach, and the error rate of adding Hanning window is lower than that of the rectangular window.