The drainage board has the functions of smooth drainage, waterproofing, root blocking, insulation, high pressure resistance, and breathability. It is mainly used for highways, railway embankments, embankments, slope protection layers, garage roof greening, rooftop gardens, football fields, golf courses, bathhouses, subway tunnels, and other projects, making construction and demolition convenient. The raw material of drainage boards is mainly high-density polyethylene, which is made by blow molding method. Therefore, drainage boards are plastic products, and the finished products have a certain spatial structure, thin plate structure, which can have conical protrusions or hollow cylindrical protrusions. A layer of filter fabric is bonded on the top surface of these protrusions to prevent soil particles from passing through, thereby avoiding channel blockage and ensuring smooth drainage of the holes. Generally, there is also a filter layer, Composed of crushed stone tiles, there is also a layer of filter layer composed of larger stones, which can effectively drain water.