Disclosed therein are an extrusion die for synthetic wood which can provide a natural wood pattern similar with real wood by forming various wood patterns on the surface of synthetic wood manufactured through extrusion molding, manufacturing apparatus and method using the same, and synthetic wood manufactured by the same. The extrusion die includes: a pair of molds respectively having rectangular extrusion holes for allowing extrudates forming an inner layer to pass through the extrusion holes; and surface layer forming parts having flow paths which are oppositely formed on contact faces of the molds in such a way as to keep a predetermined gap and formed in a top and bottom asymmetrical manner for injecting other extrudates supplied, the surface layer forming parts serving to form a surface layer having different wood patterns on the outer circumference of the inner layer. The present invention can realize the natural wood pattern similar with real wood by forming various wood patterns on the surface of the synthetic wood by the extrusion die having an asymmetric flow path therein.