A method for receiving a signal by a station (STA) in a wireless LAN system according to an embodiment of the present invention comprises the steps of: receiving a multi-user (MU) frame including a SIG-A field, a SIG-B field and a short training field (STF), and a long training field (LTF) that provides training symbols; and performing blind-decoding of the SIG-B field using a group ID assigned to the STA, wherein the SIG-B field includes information on the number of streams assigned to each of multiple stations that receive the MU frame, and the starting position of a training symbol interval for the STA in the LTF is implicitly indicated by the number of streams assigned to each of other stations in the same group, which share the group ID with the STA, and the order in which the streams are assigned to the STA in the same group.