Disclosed are a method and device for performing a sensing procedure in a wireless LAN system. According to one embodiment of the present disclosure, a method for performing a sensing procedure by a first station (STA) in a wireless LAN system comprises the steps of: receiving, from a second STA, a sensing measurement report control field comprising channel width and subcarrier grouping setting; and transmitting, to the second STA, a CSI with respect to the channel width on the basis of the subcarrier grouping setting, wherein, on the basis of which the channel width is 160MHz and the subcarrier grouping setting value is 8, a plurality of subcarriers associated with the CSI may include every eighth subcarrier in the range of subcarrier index -1012 to -12 and every eighth subcarrier in the range of subcarrier index 12 to 1012.