Embodiments of the present invention provide a data transmission method and a station. The method includes: transmitting, by a station, data of a primary access category (AC) of the station within a current transmission opportunity (TXOP), where to-be-transmitted data of the station includes the data of the primary AC and data of at least one secondary AC; after transmission of the data of the primary AC is completed, determining, by the station, whether there is remaining time in the TXOP; and if there is remaining time in the TXOP, transmitting, by the station, the data of the at least one secondary AC within the remaining time. According to the method provided in the embodiments of the present invention, the current TXOP is fully utilized without a channel resource wasted, thereby improving data transmission efficiency of the station.