Abstract: Due to the rain and snow erosion for years, the ancient wall is likely to cause lots of diseases area such as loose of brick layer and soil of internal walls, but it is a difficult problem to determine the location of these diseases, depth, size, etc. Ground penetrating radar as a non-destructive means of detecting, has features of high efficiency, high resolution, intuitive results of the detection target without causing any damage. In this paper, combined with engineering examples, using ground-penetrating radar technology to detect the ancient wall top surface. According to the processing and analysis information of GPR,selecting five representative of the radar map to carry out rod detection. Combined with the information of rod detection, carried out a comprehensive analysis to improve the accuracy of finding out disease areas, indicating the usefulness in ground-penetrating radar to detect the ancient wall.