Abstract: The watershed characteristics were analyzed based on DEM and HEC for the major processes of lowland water infilling, calculation of water flow direction, water flow accumulation, and water network layout, finally the digital basin was generated. The Chunhua watershed in Jiangning, southern Jiangsu, was taken as a case study using the new tool set. The results of the study show: the watershed boundary line is almost identical to the ridge line in the mountain areas that are less impacted by human, but the result is much different from the actual watershed in the flat areas or areas that are much impacted by human. The watershed boundary line needs to be revised artificially further. In view of efficiency and precision, it is viable to use this new tool to extract watershed characteristics.