A method for transmitting data during base station handover is provided. In the method, a User Equipment (UE) hands over a Master eNB (MeNB) from a first base station to a target base station according to a received Radio Resource Control Connection Reconfiguration (RRC CR) message; and the UE maintains a connection between the UE and a second base station unchanged and maintains a protocol entity, which corresponds to a Secondary eNB Cell Group (SCG) bearer reserved to be transmitted on the second base station, unchanged. Another method for transmitting data during base station handover, a UE, a base station, and a storage medium are also provided.