The natural brine deposit in the north of Weifang lies in the southern coast of the Laizhou bay. This place provides this deposit a great deal of resources under a arid-semiarid climate. This paper discusses the genesis of the deposit based on the geological investigation, geochemical analysis, and the former published data. The authors think that the natural brine deposit in the north of Weifang formed in a tidal environment, where sea water intruded into the area, then was concentrated by evaporation and enriched by penetration. This proposal can direct the exploitation and use of brine resources, and evaluation of resources development potential.