By carrying out the calculation and characteristic analysis of water resources balance in the Guangdong-Hong Kong-Macao Greater Bay Area，the spatial and temporal evolution trend of regional water resources were studied in this study，and the characteristics of natural resources such as water resources，inbound water resources and outbound water resources in the Guangdong -Hong Kong -Macao Greater Bay Area and the characteristics of human water development and utilization were further analyzed.The relationship between inbound water resource quantity and local runoff frequency is weak.Water use mainly relies on inbound water，while the amount of outbound water resources is abundant.The relevant research findings can provide reference for management and optimal allocation of water resources，and water security in the Guangdong-Hong Kong-Macao Greater Bay Area.