Provided are a system for implementing multiple Radio Access Networks (RANs) convergence and a method thereof in the present invention. The method includes: an anchor RAN establishes a connection with a User Equipment (UE); the anchor receives a RAB establishment request from a Core Network (CN); the anchor RAN selects an auxiliary RAN; the anchor RAN sends quality of service (QoS) parameters to the auxiliary RAN, so that the auxiliary RAN establishes a connection with the UE according to the QoS parameters, while the anchor RAN keep the connection with the UE. With the methods provided in embodiments for the present invention, multiple RANs convergence is implemented, and the UE establishes connections with the anchor RAN and the auxiliary RAN at the same time, so as to improve the peak rate of the UE.