The present invention discloses a method for accessing s network system, including the following steps: receiving, by a first network device of a first network system, a measurement report of a second network system sent by a user equipment of the first network system; determining, by the first network device, a second network device in the second network system according to the measurement report; and sending, by the first network device, a bearer setup request to the second network device, for enabling the second network device to set up a connection with the user equipment. The present invention, by realizing aggregation between a two network systems, may dynamically schedule the resources of the two network systems according to loads of the two network systems, thereby provides load balancing with extremely high efficiency, and is capable of increase the peak data rate of the user effectively and remarkably.