A method and a system for generating a key in a handover process, wherein the method comprises the following steps of: according to an evolved Node-B (eNB) (102) of a User Equipment (UE) (101), i.e. a source eNB, a mobility management entity (MME) (103) learning all adjacent eNBs of the source eNB (S130), and generating keys for the source eNB and each of the adjacent eNBs respectively (S140), encrypting the keys with a corresponding eNB public key respectively to obtain cipher texts (S150), and sending all cipher texts, keys and eNB identifiers to the UE (S160); in a handover process of the UE, a target eNB obtaining a cipher text corresponding to the target eNB from the UE and decrypting the cipher text with its own private key to obtain the key (S260).