The invention discloses a polypropylene tail gas recovery device. The polypropylene tail gas recovery device comprises a compression unit, a drying unit, a membrane separation unit and a cryogenic separation unit, wherein the compression unit, the drying unit, the membrane separation unit and the cryogenic separation unit are connected in sequence. The compression unit comprises at least one compressor, a heat exchanger and a gas and liquid separator, wherein the compressors, the heat exchanger and the gas and liquid separator are connected in sequence. The drying unit comprises at least two adsorption towers which are connected in sequence, and drying agents are placed in the adsorption towers. The membrane separation unit comprises a membrane separator. The cryogenic separation unit comprises at least one high-efficiency multi-channel heat exchanger, at least one low-temperature gas and liquid separator, at least one gas expansion device and at least one liquid expansion device. According to a polypropylene tail gas recovery method adopting expansion refrigeration, propylene in polypropylene tail gas is liquefied to be recovered, and meanwhile nitrogen is purified to meet the requirement for nitrogen recycling; in combination with a membrane separation technology, hydrogen in the polypropylene tail gas is removed; the recovery rate of the propylene in the polypropylene tail gas reaches above 98%.