Abstract: Extreme or continuous drought seriously threatens the water supply safety of important urban agglomerations. Taking the example of the Hanjiang River to Weihe River Water Diversion Project in Shaanxi Province, a water supply scheduling model for interbasin water transfer projects was constructed. Typical years and dry year groups from multiple basins, including Jialing River, Hanjiang River, and Weihe River, were selected as scheduling periods. Two schemes were set up: inter-basin water transfer from Hanjiang River to Weihe River, joint water transfer from Jialing River to Hanjiang River, and joint water transfer from Hanjiang River to Weihe River. By solving and comparing the water supply volumes of the two schemes, the water supply potential of the water transfer project in extreme dry conditions was explored. The results show that:① In 95% of extremely dry years, the joint water supply scheme can divert an additional 61 million m³ of water compared to only considering the Hanjiang River to Weihe River Water Diversion Project.② In the 3～5 year continuous dry season scenario, the joint water supply scheme can divert an additional 155 million～312 million m³ of water compared to only considering the Hanjiang River to Weihe River Water Diversion Project. The research results show that the joint water supply scheme can significantly enhance the water supply capacity, alleviate the water supply contradiction of large urban agglomerations in Guanzhong, Shaanxi, and provide scientific basis for the potential exploration of cross basin water transfer projects to cope with extreme dry season.