The utility model discloses a nozzle applied to sea water desalination. The nozzle comprises a rotational flow chamber, wherein the center at the bottom of the rotational flow is connected with a spout through a throat, the diameters of the rotational flow chamber and the spout are greater than that of the throat, and a step-like bump is arranged on the inner wall face of the spout. According to the nozzle, as the step-like bump is arranged on the inner wall face of the spout of the nozzle, when sea water entering into the rotational flow chamber is sprayed through the spout, part of sea water is separated from the wall face of the spout in advance and is distributed in a central line direction of the nozzle, so that the spraying and distributing uniformity is improved. The nozzle effectively improves the spraying and distributing uniformity, ensures a large spraying angle and enhances the work efficiency of a sea water desalination device.