Abstract: Sea water and/or saline water intrusion is one of the main geological hazards in coastal areas, which seriously constrains economic development and ecological civilization of the areas to some extent. To find out the front of sea water and/or saline water is of significance to the management of the disaster. Geophysical methods have become an important technical mean to solve this problem attributing to the convenience of operation and continuous behaviour of data acquisition. This article is devoted to the principles of the geophysical methods of high-density resistivity and EH-4, taking the southern alluvial-proluvial fan of the Laizhou Bay as a study case. Results show that both ways are effective to detecting the intrusion fronts, and the results are basically consistent with the hydro-chemical data. Testing experiment proves that the geophysical technique of three-dimensional high-density resistivity could be effectively used to identify the spatial distribution of sea water and/or saline water invasion.