Secret key generating method, main base station, auxiliary base station and user equipment

The invention relates to a secret key generating method, a main base station, an auxiliary base station and user equipment. The secret key generating method comprises the steps of determining a secret key parameter which corresponds with a DRB that is carried by wireless data; transmitting the secret key parameter to the user equipment which corresponds with the DRB so that the user equipment generates a user-plane secret key according to the secret key parameter and a basic secret key that is generated by the user equipment; receiving the basic key which is transmitted from the main base station and is generated by the main base station; and generating the user-plane secret key according to the secret key parameter and the basic secret key which is generated by the main base station.