A method and an apparatus for processing feedback information in a wireless communication system supporting a beamforming are provided. The method includes receiving reference signals for each of at least one of transmitted beams which are transmitted from a base station with respect to each received beam of the terminal, determining reception power related information for a beam combination including each of the at least one of the transmitted beams and the received beam, determining channel capacities for each beam combination targeted beam combinations of which each value is equal to or greater than a certain critical value, as a result of the determining of the reception power related information, and determining best beam related information based on the result of the determining of the channel capacities.