Abstract: The depth of brackish water is currently mainly judged by testing the salinity of the water sample or analyzing well fluid resistivity curve. The test results usually are inaccurate because they are both affected by the mixing of the liquid in the hole. In response to these problems, we propose an exploratory method for exploring the buried depth of brackish water based on the TDS test of common borehole core leaching. Through field tests of dozens of boreholes in a project in the hilly red-bed area of eastern Chengdu, the results of the burial depth of brackish water that are basically consistent with previous knowledge have been obtained. Compared with the traditional method, this method is convenient to operate with low cost, time saving and not affected by the mixed salty and brackish water. It has good applicability and promotion value in most red-bed area, especially sandstone.