The invention discloses a cyclone desander including a cylindrical drum (1), a conical drum (2) and a bracket (8), wherein the side wall of the cylindrical drum (1) is provided with a water inlet (3), the top of the cylindrical drum (1) is provided with an overflow water outlet (4), the bottom of the conical drum (2) is provided with a sewage discharge port (5), a sewage storage tank (6) is fixedly arranged on the conical drum (2), the sewage storage tank (6) and the sewage discharge port (5) are communicated, and the sewage storage tank (6) is in fixed connection with a stop valve (7). The beneficial effects of the cyclone desander are that: the stop valve is turned on only when large particle impurities gather in the sewage storage tank (6) and need to be intensively discharged, the number of times of sand discharge can be reduced, labor intensity can be reduced, water loss can be avoided, economic losses can be reduced; in addition, the spiral structural inner wall design enables the suspension in the water to gather more easily, and at the same time also enables water to spirally flow downward, so that wear is minimized, and slag removal efficiency is improved.