A method for determining a measurement gap length of a measurement gap in which a user equipment performs measurements in a dual connectivity scenario in which the user equipment, UE, may simultaneously connect to a master eNodeB and a secondary eNodeB to transmit data, comprising: determining, by a first network device, whether the master eNodeB is synchronous with the secondary eNodeB; and when the master eNodeB is synchronous with the secondary eNodeB, determining, by the first network device, that the measurement gap length is a first length; and when the master eNodeB is not synchronous with the secondary eNodeB, determining, by the first network device, that the measurement gap length is a second length; wherein the first length is less than the second length; characterised in that: the method further comprises: obtaining, by the first network device, system frame number, SFN, deviation information that is used to indicate a SFN deviation between the master eNodeB and the secondary eNodeB; wherein the determining, by the first network device, whether the master eNodeB is synchronous with the secondary eNodeB comprises: determining, by the first network device according to the SFN deviation information, whether the SFN deviation meets a synchronization condition, wherein when the SFN deviation meets the synchronization condition, the master eNodeB is synchronous with the secondary eNodeB, and or when the SFN deviation does not meet the synchronization condition, the master eNodeB is not synchronous with the secondary eNodeB; wherein the synchronization condition comprises: the system frame number, SFN, deviation is 0; or the SFN deviation is less than a first threshold; wherein the first length is 6 ms, and the second length is 7 ms. determining, by a first network device, whether the master eNodeB is synchronous with the secondary eNodeB; and when the master eNodeB is synchronous with the secondary eNodeB, determining, by the first network device, that the measurement gap length is a first length; and when the master eNodeB is not synchronous with the secondary eNodeB, determining, by the first network device, that the measurement gap length is a second length; wherein the first length is less than the second length; characterised in that: the method further comprises: obtaining, by the first network device, system frame number, SFN, deviation information that is used to indicate a SFN deviation between the master eNodeB and the secondary eNodeB; wherein the determining, by the first network device, whether the master eNodeB is synchronous with the secondary eNodeB comprises: determining, by the first network device according to the SFN deviation information, whether the SFN deviation meets a synchronization condition, wherein when the SFN deviation meets the synchronization condition, the master eNodeB is synchronous with the secondary eNodeB, and or when the SFN deviation does not meet the synchronization condition, the master eNodeB is not synchronous with the secondary eNodeB; wherein the synchronization condition comprises: the system frame number, SFN, deviation is 0; or the SFN deviation is less than a first threshold; wherein the first length is 6 ms, and the second length is 7 ms. obtaining, by the first network device, system frame number, SFN, deviation information that is used to indicate a SFN deviation between the master eNodeB and the secondary eNodeB; wherein the determining, by the first network device, whether the master eNodeB is synchronous with the secondary eNodeB comprises: determining, by the first network device according to the SFN deviation information, whether the SFN deviation meets a synchronization condition, wherein when the SFN deviation meets the synchronization condition, the master eNodeB is synchronous with the secondary eNodeB, and or when the SFN deviation does not meet the synchronization condition, the master eNodeB is not synchronous with the secondary eNodeB; wherein the synchronization condition comprises: the system frame number, SFN, deviation is 0; or the SFN deviation is less than a first threshold; wherein the first length is 6 ms, and the second length is 7 ms. determining, by the first network device according to the SFN deviation information, whether the SFN deviation meets a synchronization condition, wherein when the SFN deviation meets the synchronization condition, the master eNodeB is synchronous with the secondary eNodeB, and or when the SFN deviation does not meet the synchronization condition, the master eNodeB is not synchronous with the secondary eNodeB; wherein the synchronization condition comprises: the system frame number, SFN, deviation is 0; or the SFN deviation is less than a first threshold; wherein the first length is 6 ms, and the second length is 7 ms. the system frame number, SFN, deviation is 0; or the SFN deviation is less than a first threshold; wherein the first length is 6 ms, and the second length is 7 ms.