A method and a device for decompressing and compressing uplink data are provided. The method for decompressing uplink data includes: checking, by a decompression end, a UDC header in a PDCP packet after the PDCP packet is received, where the UDC header includes at least: compression context information of a data packet in the PDCP packet and information related to a decompression buffer area, and the information related to the decompression buffer area is for indicating the decompression end to control the decompression buffer area of the decompression end to keep consistent with a compression buffer area of a compression end; and performing, by the decompression end, a corresponding operation on the data packet in the PDCP packet according to the compression context information and the information related to the decompression buffer area.