This application discloses a multi-link establishment method and a related device. A multi-link association response frame carries radio bitmap information, to indicate an AP allowed to be associated with a radio of a STA MLD or a link allowed to be established by using a radio of a STA MLD, so that the radio subsequently switches between different APs or links. The multi-link association response frame carries link establishment status information, to indicate a link establishment status of each link that the STA MLD requests to establish, so that multi-link establishment is more flexible. The multi-link association response frame carries reassociation information, to indicate whether each parameter in association configuration information is reserved, so that a problem that signaling overheads are relatively large due to a reassociation operation is avoided. It can be learned that, in the multi-link establishment method, the foregoing information is carried to improve multi-link establishment flexibility.