The invention discloses a production line for a plastic cellular board. The production line comprises an extruder, a shaping sleeve, a laminating device, cutters, an overturning machine and a pasting device; an extrusion die is mounted at an outlet of the extruder and comprises a neck, a support plate, a transition plate and a mouth die plate, wherein the neck, the support plate, the transition plate and the mouth die plate are fixedly connected in sequence, and the mouth die plate is provided with a mold core; the neck is provided with a liquid material extrusion inlet and a flow stabilizing channel communicating with the liquid material extrusion inlet, the support plate is provided with a support plate runner, and the transition plate is provided with a compression runner; the mold core is provided with a gas flow channel; a molding runner is in butt joint with an inlet of the shaping sleeve, and an outlet of the shaping sleeve is in butt joint with an inlet of the laminating device; the cutters are located at an outlet of the laminating device; a conveyor and a gumming machine are arranged at an outlet of the overturning machine, and the gumming machine is used for gumming on front surfaces or rear surfaces of plastic cellular strips on the conveyor; a baffle which is opened at regular time is arranged at an outlet of the conveyor; and the pasting device is used for pasting an upper panel and a lower panel on a plastic cellular core.