The invention relates to a novel processing method and device for producing polyvinyl alcohol powder and belongs to the field of polyvinyl alcohol production. The method includes: PVA powder mother liquor generated after alcoholysis during polyvinyl alcohol production enters a precipitation tank from an alcoholysis machine and an extruder, is stirred by the precipitation tank and enters a mother liquor filtering machine, the solid-liquid mixture in the filtering machine is fed into a byproduct centrifuge to perform solid-liquid separation, solid is fed into a drying machine for drying, and packaging is performed. The device comprises the alcoholysis machine, a crusher, the extruder, the drying machine, a spiral conveyor, a vibration screen, a stock bin pneumatic conveying pipeline, the precipitation tank, a distribution liquid adding pump, a mother liquor delivering pump, a cyclone separator, a mother liquor filtering machine, a stock solution tank, a methanol condensing tower, a byproduct drying machine, a byproduct conveyor, a vibration screen, a packaging machine, the byproduct centrifuge, a centrifuge, a defoaming agent storage tank and a defoaming agent adding pump which are connected through pipelines. By the novel processing method and device, polyvinyl alcohol production cost is lowered, environment pollution is reduced, and potential safety hazard is eliminated.