Abstract:Northern Weifang city is near the southern coastal area of Laizhou city. It is a typical sea salt water intrusion area in China. In this paper, present condition the mechanism of sea salt water intrusion in northern Weifang city have been studied. Through data collection, special investigation of sea salt water intrusion, geological environmental monitoring and testing, the sample analysis test and indoor analysis, development and evolution history of salt water intrusion have been found out. Sea salt water intrusion development process in this area can be divided into 4 stages: the occurrence and development stage, rapid development stage, slow development stage and stable development stage. At present it is in the stable development stage. By using the test result of water quality in 2012, choosing Cl, salinity, SO24, rHCO3/rCland K+ as evaluation factors, using the method of fuzzy mathematics, present conditon of sea (salty) water intrusion in northern Weifang city has been evaluated comprehensively. Combining with the characteristics and present condition of sea salt water intrusion in work area, countermeasures for preventing sea salt water intrusion in the future have been put forward.