Engineering geological investigation plays an important role in the preparation stage of engineering construction. In order to explore the hazards of geological problems, this paper selects a water supply project in South China as the research object. Based on the mobile GIS technology, the corrosiveness of environmental water and soil to the building is analyzed through geological investigation. According to the karst phenomenon found in the survey, water pressure and water injection tests are carried out to determine the permeability of the rock body. Combined with the statistical analysis of the existing research data, it is found that the permeability of fresh rock body is less than 5Lu, except for the permeability of sandstone and sand mudstone interlayer containing soluble rock which is more than 5Lu, whereas the permeability of strongly weathered and weakly weathered rock body is between 20~80Lu, and the permeability characteristics of the rock body have the structure of “shell-core binary”.