A wet type dust collector with a rotary brush is mounted on a support. The upper portion of the left side of a circular box-shaped casing is provided with a rotary brush motor; the center of the circular box-shaped casing is provided with a main motor; the lower portion of the circular box-shaped casing is provided with a water level constancy device; a cavity containing water is formed between the right side of the casing and a front cover provided with an air suction port; the front end of the casing is provided with an exhaust port; and the lower end of the casing is provided with a blowoff valve. Besides, both the water level constancy device and a blowoff pipe are communicated with water; the center of the left side of the casing is provided with a rotary brush disk shaft; the rotary brush disk shaft is connected with a rotary brush disk by the aid of a bearing; a rotary brush motor shaft is connected with a rotary brush driving wheel; a main motor shaft is connected with a centrifugal impeller; the rotary brush disk is provided with a wheel-shaped rotary brush peripherally; the rotary brush driving wheel is connected with a rotary brush disk transmission belt; the rotary brush disk is capable of rotating on the main motor shaft; the wheel-shaped rotary brush consists of a plurality of equal-length cylindrical brushes annularly and evenly distributed on the rotary brush disk; and brush fibers are mutually crossed and overlapped, and soaked by rotating into water periodically and sequentially. The dust collector combined integrally with a fan is simple and reasonable in structure, unique in bionic design and fine in dust collecting effect.