The invention discloses an unqualified circuit board screening machine. A belt transmission mechanism is mounted on two guide rails at the top of a rack and connected with an output shaft of a main motor through a transmission shaft, a lifting motor is arranged on a locating plate, a driving belt wheel on an output shaft of the lifting motor is connected with a driven belt wheel through a belt, and the driven belt wheel is fixedly arranged on a vertical lead screw in a sleeving mode. The upper portion of the vertical lead screw is sleeved with a supporting block, two screening frames are mounted on the supporting block, the screening frames are each provided with a plurality of screening bars parallel front and back, and screening blocks are symmetrically arranged on the opposite faces of the screening bars of the screening frames on the two sides. The unqualified circuit board screening machine is simple and compact in structure, good in reliability and high in automation degree; when unqualified products are generated, a whole circuit board production line does not need to be shut down, the unqualified products on the screening machine are screened out to be put aside, the whole line can continue to carry out production, therefore, production efficiency is greatly improved, and product classification is completed well.