Solution for security negotiation during handover of a user equipment (UE) between different radio access technologies are provided. In the solution, the UE receives NAS security information and AS security information which are selected by the target system and then performs security negotiation with the target system according to the received NAS security information and AS security information. As such, the UE may obtain the key parameter information of the NAS and AS selected by a LTE system and perform security negotiation with the LTE system when the UE hands over from a different system, such as a UTRAN, to the LTE system.