The present disclosure proposes a method and an apparatus for transmitting capability information of a receiving STA in a wireless LAN system. Specifically, the receiving STA generates capability information of the receiving STA and transmits same to a transmitting STA. The capability information of the receiving STA includes an HE capabilities element and an EHT capabilities element. The HE capabilities element includes a supported channel width set field. The EHT capabilities element includes a supported EHT-MCS and NSS set field. The supported EHT-MCS and NSS set field includes first to fourth subfields. The first subfield includes information on the maximum number of spatial streams that the receiving STA can transmit and receive in each MCS when the receiving STA is a non-AP STA that operates only at 20 MHz and is allocated to a first transmission bandwidth.