Groundwater, as a precious fresh water resource, has a profound impact on the social and economic development in coastal areas. Western Yellow Sea coast (WYSC), located in the eastern part of China, is one of the most prosperous areas of China’s economic development and has a great demand for water. WYSC is currently under increasing pressure from groundwater pumped for regional development, and sustainable water management throughout the region must be based on an understanding of the hydrochemical processes that determine the quality of groundwater. This study taking WYSC as the study area, 160 groundwater samples were collected in the field and the content of Ca2+, Mg2+, Na+, K+, Cl-, SO42-, HCO3-, F, Br, δ2H and δ18O in groundwater were tested. The groundwater chemical characteristics, sources of groundwater substances, hydrogeochemical processes and the difference between the Shandong part (SDP) and Jiangsu part (JSP) were studied. The result shows that the content sequence of main cations and anions in groundwater of WYSC are Na+ > Ca2+ > Mg2+ > K+ and HCO3- > Cl- > SO42-. The hydrochemical types of WYSC groundwater are mainly Cl-Na, Cl-Ca, HCO3-Na and HCO3-Ca. The main recharge source of groundwater in the WYSC is precipitation, and the seawater and evaporation also affect the recharge process. The main sources of dissolved substances in groundwater in the WYSC are mineral dissolution, evaporation and seawater. The groundwater in SDP is affected by modern seawater intrusion, while that in JSP may be affected by ancient seawater intrusion. The dissolution and precipitation of various minerals in the groundwater in the WYSC are affected not only by regional conditions but also by seawater intrusion.