A beamforming method of a transmitter using a plurality of antenna ports in a wireless communication system, the beamforming method comprising: generating signals for beams to be transmitted through corresponding antenna ports; forming the beams by precoding the signals with beamforming vectors; sorting the beams into a plurality of resource reuse groups based on a resource that is to be shared; transmitting, to a receiver, channel state information reference signals, CSI-RSs, using the beams on CSI-RS resources determined based on the resource reuse groups, a plurality of beams included in one of the resource reuse groups being transmitted in one of the CSI-RS resources; selecting a beam having a greatest gain from the beams based on feedback information on the CSI-RSs transmitted by the receiver; and allocating a transmission resource for the selected beam, the method being characterized in that selecting the beam comprises: receiving an index of one of the resource reuse groups having a greatest gain in association with a downlink channel and a beamforming vector, from the receiver; estimating an uplink spatial correlation matrix using an uplink sounding reference signal, SRS, transmitted by the receiver; calculating an average channel gain on downlink channels using the estimated uplink spatial correlation matrix; and determining the beam having the greatest gain for the transmitter from among the plurality of beams included in the one of the resource reuse groups using the index and the average channel gain on the downlink channels. generating signals for beams to be transmitted through corresponding antenna ports; forming the beams by precoding the signals with beamforming vectors; sorting the beams into a plurality of resource reuse groups based on a resource that is to be shared; transmitting, to a receiver, channel state information reference signals, CSI-RSs, using the beams on CSI-RS resources determined based on the resource reuse groups, a plurality of beams included in one of the resource reuse groups being transmitted in one of the CSI-RS resources; selecting a beam having a greatest gain from the beams based on feedback information on the CSI-RSs transmitted by the receiver; and allocating a transmission resource for the selected beam, the method being characterized in that selecting the beam comprises: receiving an index of one of the resource reuse groups having a greatest gain in association with a downlink channel and a beamforming vector, from the receiver; estimating an uplink spatial correlation matrix using an uplink sounding reference signal, SRS, transmitted by the receiver; calculating an average channel gain on downlink channels using the estimated uplink spatial correlation matrix; and determining the beam having the greatest gain for the transmitter from among the plurality of beams included in the one of the resource reuse groups using the index and the average channel gain on the downlink channels. receiving an index of one of the resource reuse groups having a greatest gain in association with a downlink channel and a beamforming vector, from the receiver; estimating an uplink spatial correlation matrix using an uplink sounding reference signal, SRS, transmitted by the receiver; calculating an average channel gain on downlink channels using the estimated uplink spatial correlation matrix; and determining the beam having the greatest gain for the transmitter from among the plurality of beams included in the one of the resource reuse groups using the index and the average channel gain on the downlink channels.