The present invention discloses a foaming and dyeing integrated production line for a polymer material product, and a method thereof. The production line comprises a foaming and dyeing kettle, a pressure control module, a dye separation module, a fluid liquefaction and storage module, a fluid pressurization delivery module, a fluid heating module and a dyeing circulation module. The production line integrates the functions of one-step foaming and supercritical fluid dyeing of polymer material, thereby being simple in structure, comprehensive in function, convenient to operate, high in production efficiency, good in product quality and low in cost; besides, the production line can carry out both dyeing and foaming operations, only foaming operation or only dyeing operation on polymer material.