Abstract: The water intake of cold resource is an important part of the safety for nuclear power station, and it could be threatened by different blockages from the open sea. In order to prevent the blockage, this paper makes an analysis on the ocean current data of a small area near the water intake. Bases on the analysis, there are different types of ocean current near the water intake, such as semi-stable current, irregular tidal current and tidal current. The semi-stable current mainly distributes in the inlet of water intake, and there is an extension of 100 m in the south-west of the inlet. With a radius of 50 m, the irregular tidal current area locates in the outside of the inlet. The tidal current area is about 300 m outside the water intake. The residual current in the open sea is parallel with the coastal line whose direction is southwest. The velocity of residual current in the inlet of water intake is bigger than in the open sea because of the water intake. The residual current which is influenced by the tide and water intake is small near the mouth of the inlet. With a distance of 300m to the mouth of inlet, there is a net transport of residual current pointing to the water intake. The net transport of residual current area is vital to the blockage preventing.