Abstract: 2D electrical resistivity tomography is widely used in the exploration of ancient tombs, but the limitations of two-dimensional section interpretation are more and more prominent. The pseudo-3D electrical resistivity tomography based on 2D parallel or equi-angled radial lines can give three-dimensional information to a certain extent, but the requirements for surface conditions are higher and the flexibility is slightly worse.Detailed 3D information can be given by 3D electrical resistivity tomography, but the acquisition efficiency is low and it is difficult to adapt to complex surface environments. In order to solve the problem of detecting ancient mausoleums under complicated surface, a multi-azimuth pseudo-3D electrical resistivity tomography was proposed, which was applied in the detection of large ancient mausoleums in an intensive bamboo forest.According to the actual situation of the surface, 2D lines of multiple orientations can be laid out, and 2D inversion data of all orientations are merged into a pseudo 3D data volume, and 3D internal structure information is obtained by visual interpretation. The results show that the technology can adapt to the complex environment, and the pseudo-3D data can not only supplement the 2D interpretation of missing information, but also basically coincide with the drilling results.