Abstract: This paper is the result of the water resources and environmental geological survey engineering. Objective As the largest special economic zone in China, Hainan is not only the pilot free trade zone, but also the strategic fulcrum of the Maritime Silk Road, playing a pivotal role in the national strategy of "One Belt and One Road". To master the exploitation and utilization of groundwater resources and ecological environment is helpful to promote the sustainable development of Hainan. Methods This paper analyzed the situation of groundwater resources and drinking water safety in Hainan Island from the aspects of dynamic characteristics of groundwater, quantity and quality of groundwater resources, development and utilization of groundwater resources and environmental geologic problems, and probed into the main environmental geologic problems in Hainan Island. Results The average annual groundwater resources of Hainan Island is about 132.05 billion m³/a. Haikou city has the largest groundwater resources (the multi-year average is 11.33 billion m³/a), and Changjiang county has the smallest groundwater resources. The groundwater quality of Hainan Island was mainly classified as IV-V grade, and the overall water quality was poor. The main influencing factors of water quality were pH, Al and Mn. There were some environmental geologic problems in Hainan Island, such as regional water level decline, seawater intrusion and soil salinization, land desertification, mine geological environment problems. In view of the situation of groundwater resources and environmental geologic problems, some suggestions are put forward, such as carrying out hydrogeology and water resources investigation and monitoring, strengthening the economical and intensive utilization of water resources, and promoting the protection of groundwater ecological environment. Conclusions The groundwater resources in Hainan Island are relatively rich, but the water quality is poor, and the environmental geologic problems are prominent. The research results can support the sustainable utilization of water resources, ecological protection and high-quality economic and social development of Hainan Island.