利用FFT方法相继对地电、地磁、形变及重力等前兆时间序列信号进行分析，结果显示，宝昌台及乌加河台地电两测向日均值时间序列中存在3个主要谐波分量，其中周期近一年的分量物理意义明确；同一台站不同地磁测项或者不同台站同一地磁测项的分钟值时间序列中均含有周期为24小时、12小时、8小时和6小时的谐波分量，从振幅上看，24和12小时周期波占主要成分；水平摆倾斜、水管倾斜及重力分钟值时间序列中除含有半日潮汐波及日潮汐波等谐波分量外，各自还有其他周期的谐波分量。FFT方法在精确确定前兆时间序列中的干扰信息周期时具有较好的效果，在今后研究中可从方法本身、资料选取及谐波分量意义等角度深入研究。

In this paper, the time series of geoelectrical resistivity, geomagnetism, earth deformation and gravity are processed with fast Fourier transform method, “FFT” for short. There are three main harmonics in daily mean data of the earth resistivity, recorded at Baochang and Wujiahe seismostations, The harmonic with a period of approximately one year of which, has physical meaning. Different items in same geomagnetic station or same items in different geomagnetic stations, usually containe four main harmonics whose periods are 24, 12, 8 and 6 hours. Besides there exist tidal waves, there are differert harmonics in the minutes values recorded by horizontal pendulum tiltometer, water tube inclinometer, and gravimeter. It can be effective measuring the periods of noise precisely using FFT. But there are still many jobs to do in future, for example improving methods, the selection of data, explaining physical meaning of harmonic, etc.