Embodiments of this application provide a data packet decompression method. In the method, the network side device receives a first PDCP data packet, decompresses the first PDCP data packet, and sends a first buffer data identifier to the electronic device if the first PDCP data packet fails to be decompressed, where the first buffer data identifier corresponds to buffer data used for decompressing the first PDCP data packet; the electronic device receives the first buffer data identifier, and sends first buffer data corresponding to the first buffer data identifier to the network side device, where the first buffer data is buffer data used for generating the first PDCP data packet; and the network side device receives the first buffer data, and decompresses the first PDCP data packet by using the first buffer data.