An OFDM-based data transmission method, comprising: generating, by a transmitting device, a data packet, wherein the data packet comprises at least one orthogonal frequency division multiplexing OFDM symbol, wherein the OFDM symbol comprises N sequentially numbered subcarriers, the N subcarriers are divided into L subblocks, each subblock comprises └ N / L ┘ subcarriers, the └ N / L ┘ subcarriers in each subblock comprise M pilot subcarriers, start subcarriers of adjacent subblocks are adjacently numbered subcarriers, and a numbering interval is the same for adjacent subcarriers in each subblock; and each subblock is corresponding to one phase rotation signal, and signals carried on all subcarriers in each subblock are signals obtained by multiplying original signals by a corresponding phase rotation signal, wherein N is an even number, L is a positive integer, └ N / L ┘ is a positive integer, and M is a positive integer less than └ N / L ┘; and sending, by the transmitting device, the data packet; wherein numbers of the N sequentially numbered subcarriers are -N/2, (-N/2)-1,..., 0,..., (N/2)-2, and (N/2)-1; and when L=4, that start subcarriers of adjacent subblocks are adjacently numbered subcarriers is specifically: a number of a start subcarrier of a first subblock is -N/2, a number of a start subcarrier of a second subblock is (-N/2)+1, a number of a start subcarrier of a third subblock is (-N/2)+2, and a number of a start subcarrier of a fourth subblock is (-N/2)+3; wherein each subblock consists of subcarriers whose indices are at steps of the numbering interval such that the first subblock includes subcarriers with indices defined by -N/2: numbering interval:N/2-L, the second subblock includes subcarriers with indices defined by -N/2+1: numbering interval:N/2-L+1, the third subblock includes subcarriers with indices defined by -N/2+2 numbering interval:N/2-L+2, and the fourth subblock includes subcarriers with indices defined by -N/2+3: numbering interval:N/2-L+3; wherein, the method further comprises: sending, by the transmitting device, signaling, wherein the signaling is used to indicate a structure of an OFDM symbol in the data packet and a quantity of subblocks comprised in the OFDM symbol, and the structure of the OFDM symbol comprises: a division of pilot subcarriers in the OFDM symbol in each subblock and a manner in which each subcarrier in the OFDM symbol carries a signal. generating, by a transmitting device, a data packet, wherein the data packet comprises at least one orthogonal frequency division multiplexing OFDM symbol, wherein the OFDM symbol comprises N sequentially numbered subcarriers, the N subcarriers are divided into L subblocks, each subblock comprises └ N / L ┘ subcarriers, the └ N / L ┘ subcarriers in each subblock comprise M pilot subcarriers, start subcarriers of adjacent subblocks are adjacently numbered subcarriers, and a numbering interval is the same for adjacent subcarriers in each subblock; and each subblock is corresponding to one phase rotation signal, and signals carried on all subcarriers in each subblock are signals obtained by multiplying original signals by a corresponding phase rotation signal, wherein N is an even number, L is a positive integer, └ N / L ┘ is a positive integer, and M is a positive integer less than └ N / L ┘; and sending, by the transmitting device, the data packet; wherein numbers of the N sequentially numbered subcarriers are -N/2, (-N/2)-1,..., 0,..., (N/2)-2, and (N/2)-1; and when L=4, that start subcarriers of adjacent subblocks are adjacently numbered subcarriers is specifically: a number of a start subcarrier of a first subblock is -N/2, a number of a start subcarrier of a second subblock is (-N/2)+1, a number of a start subcarrier of a third subblock is (-N/2)+2, and a number of a start subcarrier of a fourth subblock is (-N/2)+3; wherein each subblock consists of subcarriers whose indices are at steps of the numbering interval such that the first subblock includes subcarriers with indices defined by -N/2: numbering interval:N/2-L, the second subblock includes subcarriers with indices defined by -N/2+1: numbering interval:N/2-L+1, the third subblock includes subcarriers with indices defined by -N/2+2 numbering interval:N/2-L+2, and the fourth subblock includes subcarriers with indices defined by -N/2+3: numbering interval:N/2-L+3; wherein, the method further comprises: sending, by the transmitting device, signaling, wherein the signaling is used to indicate a structure of an OFDM symbol in the data packet and a quantity of subblocks comprised in the OFDM symbol, and the structure of the OFDM symbol comprises: a division of pilot subcarriers in the OFDM symbol in each subblock and a manner in which each subcarrier in the OFDM symbol carries a signal.