In order to prevent a preferred frequency providing Multimedia Broadcast Multicast Service, called MBMS hereinafter, services, from getting congestion, the present invention provides a method of selecting an operating frequency for a user equipment, called UE hereinafter, in a wireless communications system. The method includes switching the operating frequency from a first frequency to a second frequency when the UE activates to receive a MBMS service of a service group; and switching the operating frequency from the second frequency to the first frequency when the UE determines not to receive any MBMS services provided on the second frequency.