A channel estimation information transmission method in a communication system, at a transmit end, comprising: determining a high efficiency long training, HE-LTF, sequence in frequency domain according to a transmission bandwidth and a mode of an HE-LTF field, for a high efficiency, HE, physical protocol data unit, PPDU, stipulated in the 802.11 ax standard; sending a time-domain signal according to a number of OFDM symbols of the HE-LTF field, N HELTF , and the determined HE-LTF sequence in frequency domain; characterized in that an HE-LTF sequence in frequency domain in a 1x HE-LTF mode over an 80 MHz bandwidth corresponds to: HE-LTF 250 (-500:4:500) = {-1, -1, +1, +1, +1, +1, +1, -1, -1, -1, +1, +1, -1, -1, +1, -1, +1, -1, -1, -1, -1, -1, -1, +1, +1, -1, -1, +1, -1, +1, -1, -1, -1, -1, -1, +1, +1, -1, -1, +1, -1, +1, -1, +1, +1, +1, +1, +1, -1, -1, +1, +1, -1, +1, -1, +1, -1, -1, -1, - 1, +1, -1, -1, -1, -1, -1, -1, +1, +1, +1, -1, -1, +1, +1, -1, +1, -1, +1, +1, +1, +1, +1, +1, -1, -1, +1, +1,-1, +1,-1, +1, +1, +1, +1,-1, +1, +1, -1, -1, +1,-1, +1,-1, +1, +1, +1, +1, +1, -1, -1, +1, +1, -1, +1, -1, +1, -1, -1, -1, -1, +1, -1, +1, -1, -1, 0, -1, +1, +1, -1, -1, +1, +1, -1, -1, +1, +1, -1, +1, -1, +1, +1, +1, +1, +1, +1, -1, -1, +1, +1, - 1, +1, -1, +1, +1, +1, +1, +1, -1, -1, +1, +1, -1, +1, -1, +1, -1, -1, -1, -1, -1, +1, +1, -1, -1, +1, -1, +1, -1, +1, +1, +1, +1, -1, +1, -1, -1, +1, -1, -1, +1, +1, +1, -1, -1, +1, +1, -1, +1, -1, +1, +1, +1, +1, +1, +1, -1, -1, +1, +1, -1, +1, -1, +1, +1, +1, +1, -1, +1, +1, -1, -1, +1, -1, +1, -1, +1, +1, +1, +1, +1, -1, -1, +1, +1, -1, +1, -1, +1, -1, - 1, -1, -1, +1, -1, +1, -1, -1, -1, +1, +1}, wherein -500:4:500 indicates that values on subcarriers with indexes -500, -496, ..., -8, -4, 0, 4, 8, ..., 496, and 500 are successively the foregoing values, and values on remaining subcarriers are 0. determining a high efficiency long training, HE-LTF, sequence in frequency domain according to a transmission bandwidth and a mode of an HE-LTF field, for a high efficiency, HE, physical protocol data unit, PPDU, stipulated in the 802.11 ax standard; sending a time-domain signal according to a number of OFDM symbols of the HE-LTF field, N HELTF , and the determined HE-LTF sequence in frequency domain; characterized in that an HE-LTF sequence in frequency domain in a 1x HE-LTF mode over an 80 MHz bandwidth corresponds to: HE-LTF 250 (-500:4:500) = {-1, -1, +1, +1, +1, +1, +1, -1, -1, -1, +1, +1, -1, -1, +1, -1, +1, -1, -1, -1, -1, -1, -1, +1, +1, -1, -1, +1, -1, +1, -1, -1, -1, -1, -1, +1, +1, -1, -1, +1, -1, +1, -1, +1, +1, +1, +1, +1, -1, -1, +1, +1, -1, +1, -1, +1, -1, -1, -1, - 1, +1, -1, -1, -1, -1, -1, -1, +1, +1, +1, -1, -1, +1, +1, -1, +1, -1, +1, +1, +1, +1, +1, +1, -1, -1, +1, +1,-1, +1,-1, +1, +1, +1, +1,-1, +1, +1, -1, -1, +1,-1, +1,-1, +1, +1, +1, +1, +1, -1, -1, +1, +1, -1, +1, -1, +1, -1, -1, -1, -1, +1, -1, +1, -1, -1, 0, -1, +1, +1, -1, -1, +1, +1, -1, -1, +1, +1, -1, +1, -1, +1, +1, +1, +1, +1, +1, -1, -1, +1, +1, - 1, +1, -1, +1, +1, +1, +1, +1, -1, -1, +1, +1, -1, +1, -1, +1, -1, -1, -1, -1, -1, +1, +1, -1, -1, +1, -1, +1, -1, +1, +1, +1, +1, -1, +1, -1, -1, +1, -1, -1, +1, +1, +1, -1, -1, +1, +1, -1, +1, -1, +1, +1, +1, +1, +1, +1, -1, -1, +1, +1, -1, +1, -1, +1, +1, +1, +1, -1, +1, +1, -1, -1, +1, -1, +1, -1, +1, +1, +1, +1, +1, -1, -1, +1, +1, -1, +1, -1, +1, -1, - 1, -1, -1, +1, -1, +1, -1, -1, -1, +1, +1}, wherein -500:4:500 indicates that values on subcarriers with indexes -500, -496, ..., -8, -4, 0, 4, 8, ..., 496, and 500 are successively the foregoing values, and values on remaining subcarriers are 0. <EOS>