Air duct of check machine capable of screening materials

The air duct of the check machine comprises a pipeline and an installation plate, installation grooves are symmetrically formed in the upper surface of the pipeline, and a primary filter plate and a secondary filter plate are installed in the two installation grooves respectively. According to the check machine air duct capable of screening the materials, the primary filter plate, the secondary filter plate and the ventilation filter plate are arranged in the pipeline, so that the materials can be screened in a classified mode through wind power; the material screening effect of the check machine air duct capable of screening the materials is improved, surface filter holes of a primary filter plate and a secondary filter plate can be cleaned through matched installation and use of a sealing mechanism and a cleaning mechanism, and then the phenomenon that the surface filter holes of the primary filter plate and the secondary filter plate are blocked is avoided; therefore, the material screening efficiency of t