Abstract: In the event of heavy rainstorm and flood,hydrological departments need to provide scientific basis and key data to flood prevention decision-making departments. In order to accurately calculate the storage capacity of rivers,reservoirs,water storage areas and water areas in the region,this paper mainly focuses on how to generate the storage capacity file corresponding to each water level in a certain region by programming batch processing the triangular network data,and generate the regional range line corresponding to a certain water level. This method is very convenient and fast in data processing. It can not only control excel software to generate relevant achievement data files,but also program screenshots to save the specified scope of the software interface,so as to achieve the perfect combination of data and graphics processing,which can provide technical support for the hydrological department in flood prevention decision-making.