Groundwater salinization is attributed either to evaporation, dissolution or mixing. Seawater intrusion falls into the latter, i.e. mixture of fresh groundwater and seawater, which implies this mixture occurs not only in the dissloved salts but also in water molecules. To confirm the occurrence of mixing, it is important to make sure that both the solvent and solute have undergone the same degree of mixing. Note that besides seawater intrusion, fresh groundwater salinization may also be attributed to evaporation and (or) dissolution. In this study, by employing both the inert (δD, δ18O, Cl- and Br-) and reactive (major and minor elements) tracers, we analyzed these chemistry data of groundwater samples collected in Laizhou Bay to identify seawater intrusion. Samples were collected from coastal aquifer of south Laizhou Bay, including 6 in Laizhou city, 10 in Longkou and 9 in Shouguang. The sediments of Laizhou and Longkou mainly consist of silicate clasts, while Shouguang is mostly covered by carboantes, which are supposed to be supplied from the southern mountainous area. By stable isotopic analyses (δD and δ18O) combining the local geographical conditions in Laizhou, the groundwater samples due to precipitation recharge were determined. We next confirmed that the groundwater samples in Longkou is also directly recharged from local precipitation, whereas for Shouguang, based on the altitude effect and the local hydrological setting, we infer the groundwater is probably recharged from the precipitation of southern mountainous area. Cl- δ18O relation indicates that salinity is originated from the dissolution of evaporite by freshwater, rather than mixing with seawater. Br-/Cl- ratios confirmed the dissolution of evaporite, and it can also reflect the influence of man made pollutants and decomposition of organic matter in transgressive sediments. As reflected by the piper digram, the Longkou samples have undergone ion exchange reactions, and ion (HCO3-, H2SiO3, F-, Li+, Sr2+ and Ba2+) concentrations, which relate to the aquifer mineral composition, also reflect extensive water rock interaction. All samples are not indicatative of mixture of fresh water and sea water. Inert tracer analyses provide a framework for regional groundwater recharge, determine that the salinization of atmosphere water is due to evaporites dissolution, and also exclude the possibility of freshwater and seawater mixing. By comparing the element concentration ratios of groundwater and marine ratios, the deviation can be explained by water rock interaction, including dissolution, precipitation, ion exchange, and contaminants enter of local samples. Therefore, for groundwater salinization study in coastal zone, the first step is to determine the possibility of solvent mixing, which is followed by identifing the solute mixing and salt sources, using various chemical tracers.