A method and apparatus for performing channel access in a WLAN system are disclosed. A method for managing a network allocation vector (NAV) by a station (STA) in a wireless LAN (WLAN) system includes: receiving a Contention Free (CF)-END frame including a duration field; if the CF-END frame is a first-type CF-END frame, resetting the NAV; and if the CF-END frame is a second-type CF-END frame, determining whether to reset the NAV according to a comparison result between a value of the duration field and a NAV value of the STA.