The activated carbon filter is a process of trapping pollutants in a suspended state in water, and the trapped suspended matter is filled in a space between the activated carbons. The pore size of the filter layer and the size of the porosity increase with the increase of the particle size of the activated carbon material. That is, the coarser the granularity of the activated carbon, the larger the space that can accommodate the suspended matter. It is characterized by enhanced filtration capacity, increased dirt holding capacity, and increased interception. At the same time, the larger the pores of the activated carbon filter layer, the more the suspended solids in the water can be transported deeper to the next layer of activated carbon filter. Under the condition of sufficient protective thickness, the suspended matter can be more trapped, and the middle and lower layers are more The interception effect is well played and the interception amount of the unit is increased.