Based on the regional geology and structure background of geothermal field in Shilipu of Jingmen City, the study on the composition isotopic of water show that geothermal water originates in atmospheric precipitation. Atmospheric precipitation supplies and forms geothermal water through a long cycle of heating process. Geothermal water sneak into a great deal of cold water in the process of migration from deep to upper because of human engineering. It must pay attention to protect geological environment in the latter development and utilization of geothermal field.