The Laxiwa Hydropower Engineering is located at high mountains and valley regions

existing high geostress in the rock masses due to the multiple-factor influences such as tectonic stress

gravity

river and weathering erosion

etc. In the river valley region

discal phenomena of drilling cores and laminated exfoliation of surrounding rock in the exploration tunnels are obvious. The determination of the 3-D geostress field in the valley region is difficult and complicated

which are tightly related to the tectonic movements in different geological period and the evolution history of river valley. In this study

detailed back analysis of the 3-D ground stress field for the engineering region is finished. Based on the results derived from the back analysis

the spatial distributing characteristics and magnitudes of the 3-D geostress field are studied. Furthermore

focused on the formation mechanisms of the geostress field

the multiple-factor influencing effects are analyzed. The paper provides a valuable reference and engineering case for the study of high geostress field and the establishments of hydropower projects located at Western China

especially for those with strong geological actions.