By analyzing the data obtained by GPS in dynamic deformation, processing analog GPS data mixed with random interference in the experiments through adopting various wavelet functions and different rank of the wavelet, and contrasting their analysis results, the suitable Daubechies function with the 'N' of six (db6) could be found. And it was used to filter GPS data of dynamic deformation, distill deformation character and separate different deformation frequency. From the processing results of actual data for large dam, we can realize db6 wavelet is advantaged to improve GPS data accuracy of dynamic deformation and its effect is notable.