Outdoor WPC square tube refers to a wood-plastic composite profile. It is a new type of composite material that uses polyethylene, polypropylene, or polyvinyl chloride as the polymer matrix, mixed with more than 50% wood flour, rice husks, or other plant fibers, along with certain additives, to form a composite material through high-temperature compounding and pelletizing. The material is then processed by extrusion molding into hollow square tubes. The products are mainly used in outdoor building structures such as gazebo exterior walls and partitions. Extruded WPC square tubes combine the natural appearance and texture of wood with the weather resistance and durability of plastic, making them a practical alternative to traditional solid wood in outdoor applications.