A network access method, a relevant device and a system are provided. The network access method includes: storing, by a UE, identifier information of a network node that the UE accesses via a first RAN; and transmitting, by the UE, a connection establishment request comprising the identifier information of the network node to a second RAN while the UE maintains the connection to the first RAN, to enable the second RAN to select the network node for the UE as a network node that the UE accesses via the second RAN.