The invention relates to the aquaculture water treatment field, in particular to an underwater particulate matter clearing device of an aquaculture system; a screen cylinder (5) formed by a filtering screen is arranged in a vertical-type cylindrical sedimentation pool (17) and is axially arranged with the sedimentation pool (17); a tangential water inlet (3) and an overflow port (10) are arrangedon the pool wall at the upper part of the sedimentation pool (17), and a drain pipe (8) is arranged at the bottom part of the sedimentation pool (17), a rotating rack (2) is arranged on an output shaft (12) of a reduction box (1) above the sedimentation pool (17), a plurality of lower extension rods (11) which are provided with screen clearers are arranged on the rotating rack (2), and the screenclearer is a hairbrush (4) or a spray head (18), and a sewage drainage mechanism is arranged below the sedimentation pool (17). The underwater particulate matter clearing device of the aquaculture system in the invention has simple structure, convenient operation, good filtering effect, low power and water consumption, low vibration and low nose, and can remove micro particles easily, thereby being suitable for automation control of a computer and prolonging the service life of the whole device.