A data transmission method and apparatus are provided. The method includes: receiving control information from a network side device, wherein the control information comprises transmission parameter indication information, wherein the transmission parameter indication information is used to indicate a quantity of transport layers for at least two codewords and port numbers of ports for the at least two codewords; and determining, based on the transmission parameter indication information, a quantity of transport layers for at least two codewords and port numbers of ports for the at least two codewords, wherein ports used by different codewords of the at least two codewords are non-quasi-co-location, and ports used by one codeword of the at least two codewords are quasi-co-location when the codeword has more than one port.