Embodiments of the present disclosure disclose a key processing method in dual connectivity mode and a device, which ensure communication security of UE in dual connectivity mode. The method according to the embodiments of the present disclosure includes: of a first base station and a second base station that have a communication connection to a terminal each, receiving, by the second base station, first request information sent by the first base station, where the first request information is used to request the second base station to generate a key used for communication with the terminal, and generating, by the second base station based on a security key carried in the first request information, the key used for communication with the terminal.