Shangjiang is one of the sites for constructing the leading dam to the middle reaches of Jinsha River Reservoir dam site. The maximum thickness of Quaternary soil is 206.2 m in the river at the possible dam site. The minimum height of the embankment dam is 249 m. The size of the dam. Construction of such dam is of a great difficulty. Through mapping, drilling, physical exploration, the work of physical and mechanical testing have revealed: (1) the bed deposits composed of the drift gravel, low liquid limit clay, gravel, fragments of stone, sand and gravel, etc; (2) the coarse-grained soil is relatively high intensity, clay of low liquid limit lower intensity, the relative weakness of the dam with the foundation for a complete; (3) the dam addresses in Longpan rift basin, where there is a major difference between the vertical structures of the neo-tectonics, and deposition area for the upper reaches of the Jinsha River. Preliminary study shows that the construction of a high earth-rock dam at the site is feasible. However, the need for the dam foundation treatment measures has to be taken by the project. The paper further discusses the effects of different programs caused by dam construction and engineering geological problems, the technology for the construction of the dam. The paper provides the geological basis for further research.