Disclosed are a method and device for implementing mobile network system handover, and a storage medium, such as: when it is determined that UE needs to perform a handover in which a core network is changed from a first core network to a second core network with the physical location of a base station remaining unchanged, a RAN can transmit a handover request message to a management device, the handover request message carrying handover indication information, thus allowing the management device to complete the handover on the basis of the handover indication information. The application of the described solution of the present invention ensures that, when the UE needs to perform the handover of the core network from the first core network to the second core network with the physical location of the base station remaining unchanged, the handover is smoothly completed.