Xinhai washing thickeners include a two-layers washing thickener and a three-layers washing thickener. Taking the three-layers washing thickener as an example, the pulp is fed by a feeding tube, and the pulp that settles freely in the rake area is further concentrated by the pressure of the scraper blade, gradually scraped towards the center of the pond, then enters the next layer pond through the mudding slot. The clear water is entered into the lowest layer for washing the material through the distribution box, the bottom of the overflow is returned to the upper layer for washing the material through the distribution box. The overflow of the first layer is discharged through the downflow dam, and the material after two times of washing is discharged through the bottom.