Eco−geological survey is a kind of foundational geological survey, which is based on regional geological survey to find out the current situation and the problems of eco−geology, study the relationship between ecological environment and geological conditions, and carry out eco−geology comprehensive evaluation. The purpose is to serve the security and management of natural resources, ecological protection and restoration. Based on the experience of eco−geological survey and exploration in Daliangshan area, this paper summarizes the ideas and technical methods of eco−geological survey and evaluation applicable to the mountainous area in SW China, and mainly obtains the following understandings: ① geological conditions are the material basis of the ecosystem, and geological conditions restrict the quality of the ecosystem and the difference of the ecological environment by restricting the eco−geological conditions such as soil, hydrology, topography, dynamic action and geological disasters. ② The soil forming parent materials in the southwest mountainous area are mainly formed by in−situ weathering or by near migration after weathering, and there is an obvious rock−soil−vegetation material transmission chain, therefore, geological conditions are an important factor restricting the ecological environment quality in this area. ③ The analysis and study of geological formations and structures is the basis of eco−geological survey in this area. ④ The purpose, task, working idea, working content, technical route and main technical methods of eco−geological survey this area put forward. This study can provide a reference case for the eco−geological survey in Southwest China, and also has a certain supporting role for the construction of the ecological geology discipline and the establishment of the eco−geological survey method system of China.