Abstract: The initial stress field is the basic data for the design and construction of large underground hydropower house. In this paper, based on the geological features, exploration data and in-situ measurement of earth stress, the initial stress field is obtained by means of finit element method and multifactor regression analysis. The characteristics of stress field is fully analyzed with respect to its sources of fromation.The results have been applied to the design of underground hydropower house and analysis of stability of the surrounding rock.