Due to the interference of diffraction wave in GPR profiles, especially in the detection of underground pipes, caves or similar anomalies, the processing and interpretation of GPR data have become very difficult. In order to deal with this problem, the authors, according to the unified wave equation form of electromagnetic wave equation and sound wave equation, used three migration methods to process GPR data. They are phase displacement, Kirchhoff integral and finite difference, which had been employed extensively in data processing of seismic prospecting. On the basis of testing and analyzing the model, the processing and analyzing of the filed GPR data yielded good results.