Abstract: The Sanchahe river basin is located in the transition zone from the Yunnan plateau to the Guizhou Plateau, which is the south tributary of the Wujiang river. The total area of the basin is 7，264 km2, where elevation drops from 2，000 m to 1，100 m. This basin hosts many multi-phase karst and diverse landforms. Within this basin, the Huayudong sub-underground river basin and the Santang sub-underground river basin are located in the karst peak-cluster region of Panxian-Weining and the karst peak forest region of central-southwest Guizhou, respectively, possessing different karst development characteristics. To investigate the relationship between karst surface morphology and structure of karst water-bearing medium, this work uses the topographic indexes (elevation and relief) of the two basins to compare and analyze their geomorphologic development features, and determine structural characteristics of the water bearing medium in the two basins by the flow recession analysis based on interval exponential function. Results show that， (1) The Huayudong underground river basin has an average elevation of 2，306 m and an average relief of 73.2 m. It can be divided into two areas: high relief area I (mean 122 m) and low relief area II (mean 64 m), which account for 14.9% and 85.1% of the whole basin area, respectively. The Santang underground river basin has an average elevation of 1，880 m and an average relief of 87.6 m. It can be divided into three areas: high relief area I (mean 106 m), medium relief area II (mean 81 m)and low relief area III(mean 48 m),which account for 40.2%, 49.7% and 10.1% of the whole basin area, respectively. (2)The recession coefficients of each stage of the Huayudong underground river basin are 0.000，3, 0.000，1, 0.000，06 (1/0.5 hour), the total water storage capacity is 2，199.356×104 m3, and the water storage of different hydrological sub-regime accounts for 0.1%, 9.9% and 90.0% of the total water storage, respectively. The recession coefficients of every stage of the Santang underground river basin are 0.001, 0.000，3 and 0.000，1 (1/0.5 hour),the total water storage capacity is 2，310.902×104 m3, and the water storage of different hydrological sub-regime accounts for 9.4%, 30.8% and 59.8%, respectively. These results suggest that there may be some correlation between surface relief and flow recession, that is, high relief corresponds to strong karst pipeline flow (the first flow recession state), and low relief corresponds to aquifers (the second and third flow recession state) with small fissures and karst cracks.