A data transmission method, comprising: when a resource position of a first data packet is preempted, generating, by a first device, first indication information, wherein the first indication information is used to indicate information about the preempted resource position of the first data packet; and sending, by the first device, the first data packet and the first indication information to a second device, so that the second device receives the first data packet based on the first indication information, characterized in that the method further comprises: determining, by the first device based on information about a preempted resource of the first data packet, a performance parameter of demodulation performed by the second device on the first data packet; determining, by the first device, second indication information based on the demodulation performance parameter, wherein the second indication information is used to indicate a data type of a second data packet, the second data packet is sent after the first data packet, and data of the first data packet is the same as data of the second data packet; and sending, by the first device, the second data packet to the second device, wherein the second data packet comprises the second indication information. when a resource position of a first data packet is preempted, generating, by a first device, first indication information, wherein the first indication information is used to indicate information about the preempted resource position of the first data packet; and sending, by the first device, the first data packet and the first indication information to a second device, so that the second device receives the first data packet based on the first indication information, characterized in that the method further comprises: determining, by the first device based on information about a preempted resource of the first data packet, a performance parameter of demodulation performed by the second device on the first data packet; determining, by the first device, second indication information based on the demodulation performance parameter, wherein the second indication information is used to indicate a data type of a second data packet, the second data packet is sent after the first data packet, and data of the first data packet is the same as data of the second data packet; and sending, by the first device, the second data packet to the second device, wherein the second data packet comprises the second indication information. determining, by the first device based on information about a preempted resource of the first data packet, a performance parameter of demodulation performed by the second device on the first data packet; determining, by the first device, second indication information based on the demodulation performance parameter, wherein the second indication information is used to indicate a data type of a second data packet, the second data packet is sent after the first data packet, and data of the first data packet is the same as data of the second data packet; and sending, by the first device, the second data packet to the second device, wherein the second data packet comprises the second indication information.