The invention relates to a production process of a plastic sheet, which is used for extrusion molding of the plastic sheet through a co-extrusion process, wherein the plastic sheet comprises a stone plastic base material layer and TPU layers respectively arranged on the upper surface and the lower surface of the stone plastic base material layer, the TPU layers are extruded and molded through physical foaming, and inert gas is selected as foaming gas. The production process of the plastic plate is environment-friendly, and can ensure the product quality.