The invention belongs to the technical field of sewage treatment and particularly relates to a sewage treatment device. The sewage treatment device comprises a collecting mechanism which collects andfilters particles, a filtering mechanism which filters the particles and a driving mechanism, wherein the collecting mechanism is mounted on one side of the filtering mechanism, and the driving mechanism is mounted on the collecting mechanism. In the using process, the sewage treatment device filters the particles in sewage through a plurality of arc-shaped grids which are distributed uniformly and the sizes of the particles are controlled by designing the arc-shaped grids in different separation distances, so that the treatment load of a follow-up structure is alleviated further and normal operation of equipment is guaranteed. The motive power of the sewage treatment device designed by the invention is provided by the filtered particles which press the grids downward, so that functions ofautomatically filtering the particles and preventing blockage of the particles are achieved. In addition, a user can filter sewage layer by layer by means of the sewage treatment device with the arc-shaped grids in gradually decreased separation distances through the up and down distributed device.