An access method and system, a user equipment, and a network side device are provided. The method includes: receiving, by a user equipment, a first message that carries an identifier of a second network access point, where the second network access point can perform air interface offloading on a first network in which a user equipment is currently located; and when the first message carries identifiers of a plurality of second network access points, selecting, by the user equipment, one second network access point from the plurality of second network access points according to first auxiliary information, and accessing the selected second network access point. By adopting the technical solutions in the embodiments of the present invention, an access delay can be effectively shortened, and access efficiency can improved, thereby effectively implementing offloading.