Abstract: In order to fully grasp the flood control situation in the Changjiang River Basin, and effectively cope with the basin flood in 2020, the Changjiang Water Resource Commission(CWRC) further strengthened the dynamic monitoring and disposal tracking of risk information based on the program of integration and sharing of information resources in comprehensive water conservancy management of Changjiang River Basin water, and upgraded the one map system for flood control, which effectively supported the 2020 flood and drought disaster prevention work. This system is supported by technologies such as geographic information systems, mobile applications and search engines, with the link of spatial information. It converges and integrates basic information of river basin flood control dispatching objects and dispatching targets, as well as monitoring information such as water conditions, water engineering conditions, dangerous conditions. It supports comprehensive information related inquiry, online monitoring and early warning, dike safety inspection, timely follow-up and treatment of danger. The one map system had provided strong support for rolling consultation and flood control deployment of CWCR in flood season. This article proposes the overall architecture, functional design and key technologies of the system construction, and summarizes the actual application effects of the system in flood control work in 2020. The research results can provide reference for maintaining the flood control safety of the river basin, implementing the new concept of disaster prevention and relief of "two insists and three changes" and promoting the development of water conservancy informatization.