<p>A method, apparatus and system for key derivation are disclosed. The method includes the following steps: a target base station) receives multiple keys derived by a source base station, where the keys correspond to multiple cells under control of the target base station; the target base station selects a key corresponding to the target cell after knowing a target cell that a user equipment (UE) wants to access. An apparatus for key derivation and a communication system are also provided.</p>
