Plate pretreatment line is a processing equipment, by which plate before process,i. e. raw material is de-rusted on appearance by casting at high speed and coated with a protective bottom paint. Anti-erode ability , anti fatigue ability and usage life of machinery products and metal parts are enhanced after plate pretreatment. At the same time, plate pretreatment can perfect craftwork on steel face as well as facilitate precision-material- falling for digital controlled shearer. Besides, because shape of plates before process is comparatively regular, it is propitious to mechanically de-rust and automatic paint-spraying, therefore pretreatment can greatly improve the efficiency of cleaning.