Embodiments of the present invention provide a data transmission method, apparatus, and device, so as to improve efficiency in utilizing a time-frequency resource. The method includes: 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; 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; 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.