Embodiments provide a method for configuring a serving cell in dual connectivity, user equipment, and a base station. According to the method, a master eNodeB sends RRC connection reconfiguration signaling to the user equipment, where the RRC connection reconfiguration signaling carries indication information used to indicate whether an SFN of the master eNodeB and an SFN of the secondary eNodeB have same parity, or carries an SFN of the secondary eNodeB. The UE executes primary secondary cell pSCell configuration at the secondary eNodeB according to the RRC connection reconfiguration signaling. The UE may determine parity of the SFN of the secondary eNodeB according to the received indication information or the SFN of the secondary eNodeB, and then the UE performs random access to the SeNB.