Embodiments of the present disclosure describe a single carrier-based data transmission method and apparatus. The method may include generating a frame and sending the frame. A data part of the frame includes 2N data blocks, the 2N data blocks are arranged in a sequence from the first data block to the 2Nth data block. Furthermore, the data block includes a payload part and a guard interval (GI), payload parts of different data blocks are separated by GIs, and a payload part of the 2Nth data block is obtained by multiplying a payload part of the (2n−1)th data block by a phase-shift sequence, where n=1, 2, . . . , N, and N is an integer greater than 0. By using the foregoing manner, data transmission robustness can be improved and data transmission for a longer distance can be supported.