Provided are a method and device for transmitting uplink data in a wireless communication. More specifically, a user equipment (UE) receives, from a first base station (BS), cell group information indicating that the first BS and a second BS are included in the same cell group. The UE receives, from the first BS, a first reference signal and assignment information regarding a first semi-persistent scheduling (SPS) resource. The UE transmits, to the second BS, a first uplink signal on the basis of the first SPS resource and the first reference signal.