Abstract: Based on the monitoring data of sea tide level and electric conductivity of S-1 well during the same period, the influence of sea tide level on seawater intrusion in Suizhong sandy plain of the west of Liaodong Bay was analyzed.The results show that the change of sea tide level has a noticeable effect on the area with heavy seawater intrusion nearby the S-1 well and the extent of seawater intrusion will increase during high sea tide period.Based on the field monitoring data about groundwater level and Cl- content in seawater intrusion transition region, it shows a significant positive correlation between the groundwater level and Cl- content with various seasons and the correlation coefficient is above 0.92.Making use of the relationship, we could found that the range of groundwater level in seawater intrusion transition region is between -2.22 m and 0.25 m in this area, which could provide indirect basis and reference on establishing the seawater intrusion section.