The invention discloses a manufacturing method of a wood veneer-plastic composite door panel. In order to realize quickly manufacturing the wood veneer-plastic composite door panel and solve the problem that a conventional hot pressing method needs long-time pressure-maintenance cooling, the invention provides the manufacturing method of the wood veneer-plastic composite door panel. According to the manufacturing method, the door panel is prepared through the steps of veneer preparation, veneer pretreatment, coupling agent coating, plastic thin film preparation, superposition for blank assembly, heating and roll extrusion, fixed-thickness cooling and edge decoration. The manufacturing method has the beneficial effects that the continuous production of the wood-plastic composite door panelis realized through carrying out hierarchical pavement on a veneer and a plastic thin film; through carrying out quick cooling molding on the door panel, the defects that a pressure-maintenance cooling process is time-consuming and energy-consuming are avoided; the production efficiency of a wooden composite door panel is improved; meanwhile, the improvement of the mechanical performance and the surface quality of a product is facilitated; in addition; a wooden raw material and plastic which are inside the door panel are also uniformly distributed and the amelioration of the mechanical performance and the surface quality of the door panel is facilitated.