Abstract: Owing to many influencing factors for in-situ stress field of large underground powerhouse region under complex geological condition，reasonable analysis and evaluation of in-situ stress field is need to integrated study about multi-source information of project site. In view of this，analytical methods and ideas of multi-source information fusion for in-situ stress field of underground powerhouse region are proposed. The typical characteristics of these methods are three-level progressive and feedback analysis of information fusion including integration of basic information, identifying of feature information，decision-making and feedback of information fusion. With the methods and ideas, characteristics of in-situ stress field of the underground powerhouse region at Guandi hydropower station and its distribution are investigated. The above results are compared with unloading damage information and monitoring information of rock mass observed in the process of site excavation，related information of numerical simulation，as well as in-situ stress measurements; it is shown that the initial stress field of the project area is reasonable. And then, the reasonableness and feasibility of the above analytical methods of multi-source information fusion for in-situ stress field are demonstrated. Finally, the analytical results from stress field can provide a basis for decision-making to a number of key issues in the process of dynamic optimization design and information construction of the large underground powerhouses

Key words: large underground powerhouse, in-situ stress, multi-source information fusion, analytical methods, distribution law