Abstract: Under the background of geological survey in key area of Tianjun county, Qinghai Province, this paper studies the technical methods and operation procedures of geological information extraction and mapping based on remote sensing image data of IRS-P6 and ETM, and other data, such as geological map, topographic map in research area. The information interpretation and extraction and mapping of hydrogeology, environmental geology, basic geology of the research area are completed by using the methods and operation procedures introduced in this paper. It shows that the method can not only help to make full use of multi-source data, improve the efficiency of geological information extraction and precision of interpretation of remote sensing information, but help save the cost, shortens working period. And it provides technology reference for the areas with inconvenient condition and traffic to carried out geological surveys and make large-scale geological maps。