The invention provides a sieving device including a grating device and a driving device, wherein the grating device has a plurality of grating units. A predetermined gap is formed between two adjacentgrating units in a first direction, and two adjacent grating units, being vertical to the first direction, are connected with each other so that the grating device is formed in a head-to-tail circular structure. The driving device drives the grating device to move in a loop reciprocating manner. Hook-shaped projections are formed on the grating device and are used for picking up foreign matters in liquid flow along with movement of the grating device. In the invention, the driving device drives the grating device to move in a looping reciprocating manner, and the grating device is provided with the hook-shaped projections, so that foreign matters in liquid flow can be picked up. The sieving device, when being arranged in a liquid flow channel, can automatically pick up the foreign mattersand avoids blocking in the channel without manual picking-up operation. The sieving device can replace human work and reduce labor intensity, and is high in production efficiency.