A data transmission method in a wireless local area network, by a communication apparatus which supports multiband transmission, the multiband comprises at least a first frequency band and a second frequency band, the second frequency band is higher than the first frequency band on frequency, wherein the method comprising: presetting, by the communication apparatus, a classification criterion, wherein the classification criterion includes a frequency band classification range corresponding to at least one of the first frequency band and the second frequency band, and the classification criterion is used by the communication apparatus to determine a target frequency band for sending each to-be-sent frame in the first frequency band and the second frequency band based on a frequency band classification range corresponding to each frequency band in the classification criterion; obtaining, by the communication apparatus, a frame whose classification attribute value comprises a frame type and a transmission rate; and determining, by the communication apparatus, the target frequency band for the obtained frame based on a frame type and a transmission rate of the obtained frame; wherein when the obtained frame is a data frame and the transmission rate is less than or equal to a preset rate classification threshold, the communication apparatus determines the first frequency band as the target frequency band of the obtained frame and sends the obtained frame by using the first frequency band; and when the classification attribute value of the obtained frame does not belong to a first frequency band classification range, the communication apparatus sends the obtained frame by using the second frequency band or the first frequency band, wherein the first frequency band classification range is a frequency band classification range corresponding to the first frequency band. presetting, by the communication apparatus, a classification criterion, wherein the classification criterion includes a frequency band classification range corresponding to at least one of the first frequency band and the second frequency band, and the classification criterion is used by the communication apparatus to determine a target frequency band for sending each to-be-sent frame in the first frequency band and the second frequency band based on a frequency band classification range corresponding to each frequency band in the classification criterion; obtaining, by the communication apparatus, a frame whose classification attribute value comprises a frame type and a transmission rate; and determining, by the communication apparatus, the target frequency band for the obtained frame based on a frame type and a transmission rate of the obtained frame; wherein when the obtained frame is a data frame and the transmission rate is less than or equal to a preset rate classification threshold, the communication apparatus determines the first frequency band as the target frequency band of the obtained frame and sends the obtained frame by using the first frequency band; and when the classification attribute value of the obtained frame does not belong to a first frequency band classification range, the communication apparatus sends the obtained frame by using the second frequency band or the first frequency band, wherein the first frequency band classification range is a frequency band classification range corresponding to the first frequency band.