Abstract: Due to the interference of diffraction waves,the position and shape of detects can not be easily interpreted.Therefore migration is very important for ground penetrating radar(GPR) data processing.The synthetic and filed GPR data are processed by the 2D finite-diffrence migration method.The study results indicated that compared to the GPR data,the spatial resolution is increased obviously using the migration method.When the diffraction energy is efficiently focused on defects,the electromagnetic wave veloctity underground can be estimated in filed GPR data.Some factors,such as velocity moded,real offset section which effect the GPR migration results are mentioned.