Embodiments of the present disclosure provide a bandwidth selection method of a WiFi technology and an AP, and in the method, the AP obtains a negotiation bandwidth negotiated by the AP and a station STA. The method includes receiving, by the AP, a data transmission request of the STA, obtaining, by the AP, a transmission bandwidth upper limit of the STA, and delivering, by the AP, a first MCS to the STA if the transmission bandwidth upper limit is less than the negotiation bandwidth, where the first MCS is less than an MCS that corresponds to the negotiation bandwidth and that is in a correspondence between a bandwidth and an MCS, and is greater than or equal to an MCS that corresponds to the transmission bandwidth upper limit and that is in the correspondence between a bandwidth and an MCS.