The District heating system (DHS) has the advantages of energy efficiency, environmental protection, and good-quality heating, so it has been widely used. There are still a series of problems. In order to improve the problem of high energy consumption during transportation, it is necessary to study the hydraulic model. The traditional method cannot satisfy the design demand of heating network. The problem can be improved by the method of the geographic information system (GIS) for the construction of modern heating network. The basic principle of hydraulic calculation in heating networks was present in the paper. Based on graph theory, a mathematical model of the hydraulic calculation for the pipeline network was established based on MapGIS.