For studying the seawater intrusion problem occurring in the littoral, a new kind of hydraulic curtain is put forward in the paper. A line of water injection wells are set along the coast line, and the ground water level will rise up for the water injection. Then the seawater will be driven back to the sea. The mechanism of the water injection hydraulic curtain is explained based on the abrupt interface model. The new kind of curtain is proved to be effective and feasible as well. Well flow theory is used to determine the parameters of the new curtain. And the elementary design method is discussed by a simple example based on the minimum consumption principle.