Solving the problem of water security in the Greater Bay Area is an important resource support for implementing the national strategy of the Guangdong-Hong Kong-Macao Greater Bay Area. At present，the per capita water resources in the Greater Bay Area are small，the distribution of space and time is severely uneven，the water efficiency is low，water resources are wasted，local water resources are over-exploited，and some river sections are seriously intertwined with new and old issues. The new connotation of water resources security and new topics have been proposed. To formulate relevant policies on water resources security in the Guangdong-Hong Kong-Macao Greater Bay Area，we must implement President Xi’s thoughts on water management in the new period，and adhere to the “water saving priority，space balance，system governance，and two-handed efforts” to promote urban and rural living. We will continue to make efforts to adjust the structure of industrial water use，expand the amount of recycled water used，improve water price policies，strengthen water pollution prevention，improve water conservancy facilities，and improve the water resources management system to build a water resources security policy system.