A method and apparatus for transmitting and receiving a frame supporting a short MAC header in a wireless LAN (WLAN) system are disclosed. A method for encrypting a MAC protocol data unit (MPDU) in a wireless LAN (WLAN) system includes: constructing, by a first station (STA), Additional Authentication Data (AAD) including a Frame Control (FC) field, an Address 1 (A1) field, an Address 2 (A2) field, and a Sequence Control (SC) field; and transmitting a frame including an encrypted MPDU including the AAD from the first STA to a second STA. The FC field, the A1 field, the A2 field, and the SC field of the AAD are constructed on the basis of an FC field, an A1 field, an A2 field, and an SC field of a short MAC header of the MPDU, and one of the A1 field and the A2 field of the AAD includes an associated identifier (AID) value according to whether a transmission direction of the frame is an uplink (UL) or downlink (DL) direction.