The Nanshan defense line of the Ming Great Wall in Yanqing of Beijing and Huailai of Hebei was a significant defense facility guarding the Thirteen Ming Tombs. Previous satellite images revealed the addition of three parallel trenches in a special form along parts of the Nanshan defense line. With the application of remote sensing techniques such as imagery registration, drone photography and 3D reconstruction, the distribution of trenches could be mapped with high precision and the digital elevation maps of local trenches could be generated. The trenches are mainly distributed on the plain north of the mountain, controlling runoff outlets and major river valleys, and improving the defense function of the Great Wall defense line by increasing the overcoming difficulty. The three additional trenches in a special form outside the Great Wall were built as a defense facility to guard the important strategic position for the Thirteen Ming Tombs.