A method for aggregation transmission of multi-user downlink data in a URLLC application scenario, wherein the method is performed by a first communications apparatus, the first communications apparatus is a first terminal device or a module of the first terminal device, and the method comprises: receiving first indication information from a network device, wherein the first indication information indicates location information of first downlink data of the first terminal device in a first downlink bit sequence, the first downlink bit sequence comprises downlink data of each of N terminal devices, the first terminal device is one of the N terminal devices, and N is an integer greater than 1; receiving second indication information from the network device, wherein the second indication information comprises information about a first time-frequency resource; receiving a second downlink bit sequence on the first time-frequency resource; performing channel decoding on the second downlink bit sequence to obtain the first downlink bit sequence; and obtaining the first downlink data based on the first indication information and the first downlink bit sequence; wherein the method further comprises: obtaining (S 106a) first location information, wherein the first location information is location information of first check information in the first downlink bit sequence, the first location information is different from second location information, the second location information is location information of second check information in the first downlink bit sequence, the first check information is a parity bit of the first downlink data, the second check information is a parity bit of second downlink data, the second downlink data is downlink data of a second terminal device, and the second terminal device is a terminal device other than the first terminal device in the N terminal devices; and determining the first check information based on the first location information and the first downlink bit sequence. receiving first indication information from a network device, wherein the first indication information indicates location information of first downlink data of the first terminal device in a first downlink bit sequence, the first downlink bit sequence comprises downlink data of each of N terminal devices, the first terminal device is one of the N terminal devices, and N is an integer greater than 1; receiving second indication information from the network device, wherein the second indication information comprises information about a first time-frequency resource; receiving a second downlink bit sequence on the first time-frequency resource; performing channel decoding on the second downlink bit sequence to obtain the first downlink bit sequence; and obtaining the first downlink data based on the first indication information and the first downlink bit sequence; wherein the method further comprises: obtaining (S 106a) first location information, wherein the first location information is location information of first check information in the first downlink bit sequence, the first location information is different from second location information, the second location information is location information of second check information in the first downlink bit sequence, the first check information is a parity bit of the first downlink data, the second check information is a parity bit of second downlink data, the second downlink data is downlink data of a second terminal device, and the second terminal device is a terminal device other than the first terminal device in the N terminal devices; and determining the first check information based on the first location information and the first downlink bit sequence. obtaining (S 106a) first location information, wherein the first location information is location information of first check information in the first downlink bit sequence, the first location information is different from second location information, the second location information is location information of second check information in the first downlink bit sequence, the first check information is a parity bit of the first downlink data, the second check information is a parity bit of second downlink data, the second downlink data is downlink data of a second terminal device, and the second terminal device is a terminal device other than the first terminal device in the N terminal devices; and determining the first check information based on the first location information and the first downlink bit sequence.