An interference avoidance method performed by an Access Point (AP) in a WLAN system in an Overlapping Basic Service Set (OBSS) environment is provided. The interference avoidance method includes receiving an interference avoidance request message from the first STA, the interference avoidance request message informing that frame transmission of the AP acts as interference with a first STA; transmitting an interference avoidance response message in response to the interference avoidance request message; obtaining first channel information about a first channel between the first STA and the AP from the first STA which has received the interference avoidance response message; determining a transmitting steering matrix based on the first channel information; and transmitting data to a second STA by performing beamforming according to the transmitting steering matrix.