Composite drainage network (also known as three-dimensional composite drainage network, drainage grid) is a new type of drainage geomaterials. High density polyethylene (HDPE) is used as raw material and processed by special extrusion molding process. It has three layers of special structure. The middle bar is rigid and vertically arranged to form a drainage channel. The upper and lower cross-arranged bars form a support to prevent geotextiles from embedding in the drainage channel, and can maintain high drainage performance even under high loads. The composite use of double-sided adhesive permeable geotextile has the comprehensive performance of “reverse filtration, drainage, air permeability and protection”, which is the most ideal drainage material at present.