The present invention relates to a method and device for channel measurement in a wireless LAN system. A station (STA) receives a plurality of sounding frames from an access point (AP), estimates the plurality of sounding frames in order to generate long-term channel state information (LCSI), provides the generated LCSI to the AP as feedback, and receives from the AP a group identifier (ID) management frame comprising information on a group ID determined on the basis of the LCSI.