A method, device and system for implementing optimized inter-RAT handover are disclosed. When a user equipment or a source network prepares for a handover to a target network, a corresponding target network ID is obtained from a configured mapping between cell IDs and target IDs according to a received cell ID, target network bearers are established following identification of an access node of the target network, and the user equipment is connected to the target network after handover preparation is complete. With the present invention, when a user equipment is handed-over from a source network to a target network, service continuity can be maintained with an enhanced quality of user experience.