The invention discloses a dry gas recovery system and method for a refinery plant. The system comprises a compressor, an absorption tower, a re-absorption tower, a stripping tower, a liquefying cooler and a flash tank, wherein the compressor is connected with a heat exchanger, and is then connected with the absorption tower; the top part of the absorption tower is connected with the re-absorption tower, and the bottom part of the absorption tower is connected with the stripping tower; the liquefying cooler and the flash tank are sequentially connected with the top part of the stripping tower; and the top part of the flash tank is connected with the inlet of the compressor. The method comprises the steps of compressing, cooling, absorbing, stripping and liquefying dry gas of the refinery plant to obtain carbon 2-enriched products. The method has the advantages of a little equipment, low energy consumption, simple flow and high recovery rate, and the product is easy to store and transport.