A method for multi-user transmission in a wireless LAN system according to one embodiment of the present specification comprises the steps of: individually performing, by a STA including a first directional antenna and a second directional antenna, a first countdown procedure for the first directional antenna and a second countdown procedure for the second directional antenna according to a directional CCA operation for the first and second directional antennas; determining the first directional antenna as a primary antenna when the first countdown procedure is completed before the second countdown procedure; determining whether the second directional antenna is idle from a threshold time before a completion time point of the first countdown procedure to the completion time point; and transmitting multiple streams on the basis of the first and second directional antennas according to the result of the determination.