A data transmission method, comprising the steps of: determining, by a network device, from a first set comprising a plurality of demodulation reference symbol DMRS port combinations applicable to different application scenarios, demodulation reference symbol DMRS port combinations that are not applicable to an application scenario in order to reduce signaling overheads for the application scenario, selecting, by the network device, from the first set, a second set for the application scenario based on the determined demodulation reference symbol DMRS port combinations, wherein each DMRS port combination in the second set belongs to the first set, a quantity of DMRS port combinations comprised in the second set is less than a quantity of DMRS port combinations comprised in the first set and the DMRS port combination comprises at least one DMRS port; generating, by the network device, first information, wherein a value of one or more bits comprised in the first information is used to indicate a demodulation reference symbol DMRS port combination in the second set; and sending, by the network device, the first information to a terminal device, wherein the method further comprises the step of: sending, by the network device, before the first information is sent to the network device, second information to the terminal device, wherein the second information is used for the terminal device to determine all DMRS port combinations comprised in the second set, characterized in that the second information comprises a plurality of bits, and each bit in the plurality corresponds to one group of DMRS ports and is used to indicate whether DMRS ports of that group are included in at least two DMRS port combinations comprised in the second set, wherein, for each bit, all DMRS ports of the corresponding group of DMRS ports share the same time-frequency resource location occupied by the DMRS or a same frequency-domain orthogonal codes occupied by the DMRS or a same time-domain orthogonal codes occupied by the DMRS. determining, by a network device, from a first set comprising a plurality of demodulation reference symbol DMRS port combinations applicable to different application scenarios, demodulation reference symbol DMRS port combinations that are not applicable to an application scenario in order to reduce signaling overheads for the application scenario, selecting, by the network device, from the first set, a second set for the application scenario based on the determined demodulation reference symbol DMRS port combinations, wherein each DMRS port combination in the second set belongs to the first set, a quantity of DMRS port combinations comprised in the second set is less than a quantity of DMRS port combinations comprised in the first set and the DMRS port combination comprises at least one DMRS port; generating, by the network device, first information, wherein a value of one or more bits comprised in the first information is used to indicate a demodulation reference symbol DMRS port combination in the second set; and sending, by the network device, the first information to a terminal device, wherein the method further comprises the step of: sending, by the network device, before the first information is sent to the network device, second information to the terminal device, wherein the second information is used for the terminal device to determine all DMRS port combinations comprised in the second set, characterized in that the second information comprises a plurality of bits, and each bit in the plurality corresponds to one group of DMRS ports and is used to indicate whether DMRS ports of that group are included in at least two DMRS port combinations comprised in the second set, wherein, for each bit, all DMRS ports of the corresponding group of DMRS ports share the same time-frequency resource location occupied by the DMRS or a same frequency-domain orthogonal codes occupied by the DMRS or a same time-domain orthogonal codes occupied by the DMRS. sending, by the network device, before the first information is sent to the network device, second information to the terminal device, wherein the second information is used for the terminal device to determine all DMRS port combinations comprised in the second set, characterized in that the second information comprises a plurality of bits, and each bit in the plurality corresponds to one group of DMRS ports and is used to indicate whether DMRS ports of that group are included in at least two DMRS port combinations comprised in the second set, wherein, for each bit, all DMRS ports of the corresponding group of DMRS ports share the same time-frequency resource location occupied by the DMRS or a same frequency-domain orthogonal codes occupied by the DMRS or a same time-domain orthogonal codes occupied by the DMRS.