The detections of reinforcement and target are affected by shallow buried reinforcement in concrete member with ground penetrating radar(GPR)testing defects. It is of great importance to study the cause and elimination of the interference. Based on the theoretical calculation, the numerical experimentations were designed, and the reinforcement detection was simulated by embedding reinforcement of different depths in the sand tank. Moreover, the signal was processed by various migration methods. The results show that the interference is relevant with the length of shallow reinforcement within GPR detection area. By comparing with diffraction stack, Kirchoff and F-K migration methods, Tau-p domain migration can deal with the reinforcement detection signal better. The position of reinforcement is more accurately identified. The 3D image of GPR become flat and clean through Tau-p domain migration. Finally,the GPR data in a practical project was well analyzed by Tau-p migration.