Abstract: The southeastern margin of the Tibetan Plateau has experienced Tethys accretion orogeny and collision orogeny between the Indian continent and Eurasian continent, making it one of the typical regions of lateral collision between the Indian and Asian plates in the Cenozoic. Multiple complex tectonic movements have led to the widespread development of various metallic and non-metallic minerals, which formed the Sanjiang metallogenic belt. The lithosphere is the main carrier for recording continental tectonic evolution and mineralization. Revealing the layers’ structure of the lithosphere is of enormous significance for understanding the Tethyan evolution in the Sanjiang area, the dynamic process of the formation of the Tibetan Plateau, and the ore formation processes in the southeastern Tibetan Plateau. In this paper, we systematically review the research outcomes of seismic detection of crustal and mantle structures on the southeastern margin of the Tibetan Plateau. We obtained the lithospheric bottom interface, Moho depth, and upper crustal thickness (basement boundary) in the Sanjiang area through systematic sampling and interpolation. The results show that the overall variation of the basement interface in the study area overall varied intensely, exhibiting mirror symmetry with the Moho interface. The Moho depth gradually deepens from south to north. The thickness of the lithosphere is generally thin in the southwest and thick in the northeast, with an overall thickness range of 60～190 km.