Abstract: The preprocessing of tidal gravity observation data is very important to obtain high-quality tidal harmonic analysis results.The preprocessing methods of tidal gravity observation data are studied systematically,and average filtering method and wavelet filtering method for downsampling original tidal gravity observation data are given in the paper,as well as the linear interpolation method and the cubic spline interpolation method for processing interrupt data.The automatic preprocessing software of the tidal gravity observation data(APTsoft) is developed,which can calibrate and correct automatically abnormal data such as spikes,steps and interrupts.Finally,the experimental results show that the preprocessing methods and APTsoft are very effective,and APTsoft can be applied to the automatic preprocessing of tidal gravity observation data.