Embodiments of the present invention provide an SeNB key update method, including: establishing, by an MeNB, an RRC connection to UE, and determining a first SeNB and a second SeNB that are connected to the UE; calculating, by the MeNB, a key S-KeNB1 of the first SeNB and a key S-KeNB2 of the second SeNB, and sending an SeNB addition request to the first SeNB and the second SeNB; receiving, by the MeNB, a first request acknowledgment message fed back by the first SeNB, and receiving a second request acknowledgment message fed back by the second SeNB; and sending, by the MeNB, an RRC reconfiguration request to the UE according to the first request acknowledgment message and the second request acknowledgment message, where the RRC reconfiguration request includes key update information of the first SeNB and key update information of the second SeNB.