Disclosed in the present invention is a method for dynamically changing mobile networks, comprising: a subscription data manager (SM) transmitting to a first mobile network a mobile network changing message used for indicating that user equipment (UE) needs to change the network; from the first mobile network, the SM receiving a notification signaling message used for notifying the SM of the access of the UE to the first mobile network; and the SM transmitting the mobile network changing message to the UE via the first mobile network, in order to indicate the UE to accomplish a change to a second mobile network. Also disclosed in the present invention are a subscription data manager and user equipment. The present invention reaches the effect that the operator mobile network of UE with an eUICC (embedded Universal Integrated Circuit Card) installed therein is dynamically changed by a service provider as needed, and in particular, the operator mobile network can still be changed by the method provided in the embodiment of the present invention even when the UE misses a period for changing the operator mobile network due to power outage, equipment shutdown or other situations.