Groundwater function zoning is an important means to ensure that groundwater plays its various functions, which can provide a scientific basis for the protection and development of groundwater resources. Water resources are scarce in the Central Plains Urban Agglomeration (CPUA), so it is of great significance to evaluate groundwater vulnerability and to zone groundwater function in this area. In this study, the resource supply function (RSF), eco-environment function (EEF), and geo-environment function (GEF) of groundwater were analyzed using the analytic hierarchy process (AHP), maximum method, and dominant mark method, so as to divide the shallow groundwater function in the plain of the CPUA. The results show that the reservation areas (32.0%) are distributed in the areas from Luoning County to Yanjin County, Changyuan County to Xinzheng County, and the areas near mountainous in the south of the CPUA. The geological-disaster-prone areas (29.5%) are distributed in the areas from Ruyang County to Luohe City, Weihui County to Jiyuan City, Xingyang County to Changge County, Changyuan County to Yuanyang County, and Kaifeng City. The development and utilization areas (6.4%) are distributed near mountainous areas in the CPUA. The ecologically vulnerable areas (7.5%) are distributed in the east of Kaifeng City and the northeast of Xinxiang City. The conservation areas (24.6%) are distributed in the areas from Ruyang County to Wuyang County, Xinzheng County to Xingyang County, the north of Xuchang City, the east of Luohe City, Kaifeng City, and Xinxiang City. In order to better manage the groundwater, this study evaluates the vulnerability of the groundwater using the DRASTIC model and makes a single indicator sensitivity analysis. The results show that the accuracies of indicators D, A, and I are particularly important for this vulnerability evaluation. According to the groundwater vulnerability and the land use types, some suggestions were put forward. The research results can provide a reference for groundwater management and development in the CPUA and other areas.