According to an embodiment of the present invention, after a macro base station judges to switch a user plane bearer of user equipment, according to a differentiating parameter of a target base station and a temporary key shared by the macro base station and the user equipment, the macro base station generates a key used for the communication between the target base station and the user equipment; and the macro base station sends the differentiating parameter to the user equipment so as to enable the user equipment to generate a key used for the communication between the user equipment and the target base station according to the differentiating parameter and the temporary key shared by the macro base station and the user equipment.