When the spiral sand washing machine is working, the motor drives the impeller to slowly rotate through a triangular belt, reducer, and gear, and the sand and gravel enter the washing groove through a feeding groove. Driven by the impeller, they roll and grind each other to remove impurities that cover the surface of the sand and gravel, while also damaging the water vapor layer that covers the sand particles, in order to facilitate dewatering; At the same time, add water to form a strong water flow, timely remove impurities and small specific gravity foreign objects, and discharge them from the overflow outlet washing tank to complete the cleaning function. Clean sand and gravel are taken away by the blades, and then poured into the discharge groove from the rotating impeller to complete the cleaning effect of the sand and gravel.