The invention discloses a small dust particle screening and winnowing device which comprises a dust screening module and an accumulated dust winnowing module, wherein the dust screening module comprises a motor, an eccentric wheel, a double-layer screen module and the like; the accumulated dust winnowing module comprises a dust eduction tube, an accumulated dust winnowing container, a weighing module and the like. The accumulated dust winnowing container is filled with dust, the required dust weight is set in a controller, the motor is started to drive an eccentric block to do circular motion, and the dust container does reciprocating vibration vertically and swings from side to side under the effect of two pairs of springs with different heights on a base. The screening of dust in a limited size range is realized through a double-layer dust screen; a blower is controlled to blow screened dust into the accumulated dust winnowing container through the dust eduction tube and then enable the dust to uniformly deposit on a sample until the dust weight reaches the set value. With adoption of the device, the dust granularity can be screened to automatically control dust winnowing, and the consistency of the dust granularity and the distribution uniformity of sample accumulated dust are effectively improved.