In an information transmission method, a sending device sends a data frame to a receiving device. The data frame occupies a transmission resource block, a bandwidth occupied by the transmission resource block is greater than 160 MHz, and the data frame comprises resource unit RU allocation information. The sending device determines indication information based on a resource block size indicated by the RU allocation information and a location of a 160 MHz channel within the bandwidth occupied by the transmission resource block, with the 160 MHz channel having more data tones in the transmission resource block. The sending device determines a response resource block based on the indication information and the RU allocation information, and then receives an acknowledgment frame for the data frame from the receiving device on the response resource block.