A data transmission method, wherein the method comprises: determining, by a transmit end device, a signature matrix S according to a quantity L of layers of a data stream and a quantity R of receive antennas used by a receive end device, wherein the signature matrix S comprises L first element sequences arranged in a first dimensional direction, the L first element sequences are in one-to-one correspondence with the L layers of the data stream, each first element sequence comprises R first elements arranged in a second dimensional direction, the R first elements are in one-to-one correspondence with the R receive antennas, the R first elements comprise at least one zero element and at least one non-zero element, R≥2, the L first element sequences are different from each other, the L layers of the data stream correspond to a same time-frequency resource, and L≥2; determining, by the transmit end device, a precoding matrix P according to a channel matrix H and the signature matrix S, and performing precoding processing on the L-layer data stream according to the precoding matrix P, wherein the channel matrix H corresponds to channels between the transmit end device and the receive end device, the precoding matrix P comprises L second element sequences arranged in the first dimensional direction, the L second element sequences are in one-to-one correspondence with the L first element sequences, and the L second element sequences are in one-to-one correspondence with the L layers of the data stream; and sending, by the transmit end device to the receive end device, the L-layer data stream on which the precoding processing has been performed and information used to indicate the signature matrix S. determining, by a transmit end device, a signature matrix S according to a quantity L of layers of a data stream and a quantity R of receive antennas used by a receive end device, wherein the signature matrix S comprises L first element sequences arranged in a first dimensional direction, the L first element sequences are in one-to-one correspondence with the L layers of the data stream, each first element sequence comprises R first elements arranged in a second dimensional direction, the R first elements are in one-to-one correspondence with the R receive antennas, the R first elements comprise at least one zero element and at least one non-zero element, R≥2, the L first element sequences are different from each other, the L layers of the data stream correspond to a same time-frequency resource, and L≥2; determining, by the transmit end device, a precoding matrix P according to a channel matrix H and the signature matrix S, and performing precoding processing on the L-layer data stream according to the precoding matrix P, wherein the channel matrix H corresponds to channels between the transmit end device and the receive end device, the precoding matrix P comprises L second element sequences arranged in the first dimensional direction, the L second element sequences are in one-to-one correspondence with the L first element sequences, and the L second element sequences are in one-to-one correspondence with the L layers of the data stream; and sending, by the transmit end device to the receive end device, the L-layer data stream on which the precoding processing has been performed and information used to indicate the signature matrix S.