The utility model discloses an extrusion mould for manufacturing a plastic wood sectional bar. The extrusion mould for manufacturing the plastic wood sectional bar is matched with an extruder, and comprises a coextrusion mould body, a pre-molding mould body and a stock mould body; the coextrusion mould body is connected with the extruder; one side of the pre-molding mould body is connected with the tail end of the stock mould body, and the other side of the pre-molding mould body is connected with the coextrusion mould body; the pre-molding mould body comprises two sections, one end of the first pre-molding mould body is connected with the coextrusion mould body, and the other end of the first pre-molding mould body is fixedly arranged on the second pre-molding mould body connected with the stock mould body; and the contacted inner surface of the two pre-molding mould bodies is provided with a coextrusion runner. The coextrusion mould regulates the flow speed and pressure in a mould body effectively, so that the sectional bar is internally and externally cooled and shaped uniformly.