The invention discloses a mechanical device used for cleaning enteromorpha. The mechanical device comprises a left baffle, a right baffle, an arc-shaped screen plate, a licker-in and an annular conveyor belt, wherein the central axis of an upper roller, the central axis of a lower roller and the central axis of the licker-in are located in the same plane; the arc-shaped screen plate is provided with a gap part, and the section of the arc-shaped screen plate is approximately in a C shape; the licker-in is coved with the arc-shaped screen plate, and a gap is reserved between the licker-in and the arc-shaped screen plate; the space between the inner sides of the two end faces of the gap part of the arc-shaped screen plate and the surface of the arc-shaped screen plate are all provided with a plurality of strip-shaped holes with the same quantity, and the strip-shaped holes are all matched with all row thorns on a body of the licker-in both in position and width; and when the licker-in rotates, interference does not occur to the row thorns and all the strip-shaped holes. The mechanical device is matched with an external barge or vehicle for use and is simple in structure, stable in operation, high in enteromorpha cleaning efficiency and low in manufacturing cost and operation cost.