A method for distinguishing data formats, comprising: receiving, by a terminal, a downlink data packet, and determining, by the terminal, whether a data format of the downlink data packet is a first data format or a second data format, wherein the downlink data packet is in the first data format if the downlink data packet is encrypted with a first key of a source base station and compressed with a first ROHC profile of the source base station, and the downlink data packet is in the second data format if the downlink data packet is encrypted with a second key of a target base station and compressed with a second ROHC profile of the target base station, wherein the determining, by the terminal, whether the data format of the downlink data packet is the first data format or the second data format comprises: determining, by the terminal through a Radio Link Control, RLC, entity corresponding to the downlink data packet, whether the data format of the downlink data packet is the first data format or the second data format, wherein the downlink data packet of the source base station is borne on a first RLC entity of the terminal, and the downlink data packet of the target base station is borne on a second RLC entity of the terminal, and wherein the determining, by the terminal through the RLC entity corresponding to the downlink data packet, whether the data format of the downlink data packet is the first data format or the second data format comprises: determining by the terminal that the data format of the downlink data packet is the first data format when the downlink data packet received by the terminal is borne on the first RLC entity of the terminal; and determining by the terminal that the data format of the downlink data packet is the second data format when the downlink data packet received by the terminal is borne on the second RLC entity of the terminal. receiving, by a terminal, a downlink data packet, and determining, by the terminal, whether a data format of the downlink data packet is a first data format or a second data format, wherein the downlink data packet is in the first data format if the downlink data packet is encrypted with a first key of a source base station and compressed with a first ROHC profile of the source base station, and the downlink data packet is in the second data format if the downlink data packet is encrypted with a second key of a target base station and compressed with a second ROHC profile of the target base station, wherein the determining, by the terminal, whether the data format of the downlink data packet is the first data format or the second data format comprises: determining, by the terminal through a Radio Link Control, RLC, entity corresponding to the downlink data packet, whether the data format of the downlink data packet is the first data format or the second data format, wherein the downlink data packet of the source base station is borne on a first RLC entity of the terminal, and the downlink data packet of the target base station is borne on a second RLC entity of the terminal, and wherein the determining, by the terminal through the RLC entity corresponding to the downlink data packet, whether the data format of the downlink data packet is the first data format or the second data format comprises: determining by the terminal that the data format of the downlink data packet is the first data format when the downlink data packet received by the terminal is borne on the first RLC entity of the terminal; and determining by the terminal that the data format of the downlink data packet is the second data format when the downlink data packet received by the terminal is borne on the second RLC entity of the terminal. determining, by the terminal through a Radio Link Control, RLC, entity corresponding to the downlink data packet, whether the data format of the downlink data packet is the first data format or the second data format, wherein the downlink data packet of the source base station is borne on a first RLC entity of the terminal, and the downlink data packet of the target base station is borne on a second RLC entity of the terminal, and wherein the determining, by the terminal through the RLC entity corresponding to the downlink data packet, whether the data format of the downlink data packet is the first data format or the second data format comprises: determining by the terminal that the data format of the downlink data packet is the first data format when the downlink data packet received by the terminal is borne on the first RLC entity of the terminal; and determining by the terminal that the data format of the downlink data packet is the second data format when the downlink data packet received by the terminal is borne on the second RLC entity of the terminal. determining by the terminal that the data format of the downlink data packet is the first data format when the downlink data packet received by the terminal is borne on the first RLC entity of the terminal; and determining by the terminal that the data format of the downlink data packet is the second data format when the downlink data packet received by the terminal is borne on the second RLC entity of the terminal.