Provided are a method and device for performing joint transmission in wireless LAN system. Particularly, an M-AP transmits a first control frame for informing of joint transmission to first and second S-APs. The M-AP transmits a data frame to the first and second S-APs. The M-AP transmits a second control frame, comprising scheduling information necessary for joint transmission, to the first and second S-APs. The M-AP performs joint transmission to an STA by means of the first and second SAPs. The data frame is transmitted to the STA from the first and second S-APs by means of joint transmission.