The present application discloses an access method, apparatus, device, and system, and belongs to the field of communications technologies. The method includes: receiving, by a selection function entity SFE, an access request of user equipment UE sent by a radio access network node RAN node; determining a usage type of the UE based on the access request of the UE; and selecting, for the UE based on the usage type of the UE, a node that is in a dedicated core network and that can serve the UE, where the node that is in the dedicated core network and that can serve the UE corresponds to the usage type of the UE. Therefore, a node accessed by the UE is the node in the dedicated core network corresponding to the UE, and this ensures that the node can complete security verification of the UE.