A method for repeated transmission, comprising: determining, by a terminal device, a transmission time unit used in the first transmission of a data packet, wherein the determined transmission time unit is a transmission time unit in which a grant-free transmission resource is located and that is between two adjacent specific transmission time units, and is not the first transmission time unit in which a grant-free transmission resource is located and that is between the two adjacent specific transmission time units, wherein multiple transmission time units comprise grant-free transmission resources between the two adjacent specific transmission time units, wherein a period of the specific transmission time unit in a time domain resource is Q transmission time units, wherein the specific transmission time unit is a transmission time unit in which a repeated transmission procedure is forcibly terminated, and Q is an integer greater than 2; determining, by the terminal device based on the determined transmission time unit and the parameter Q, a hybrid automatic repeat request HARQ process used to transmit the data packet; and when repeated transmission of the data packet is not terminated before the latter specific transmission time unit in the two adjacent specific transmission time units, performing, by the terminal device starting from the determined transmission unit by using the HARQ process, one transmission of the data packet in each transmission time unit in which a grant-free transmission resource is located until a transmission of the data packet is performed for the last time in the latter specific transmission unit. determining, by a terminal device, a transmission time unit used in the first transmission of a data packet, wherein the determined transmission time unit is a transmission time unit in which a grant-free transmission resource is located and that is between two adjacent specific transmission time units, and is not the first transmission time unit in which a grant-free transmission resource is located and that is between the two adjacent specific transmission time units, wherein multiple transmission time units comprise grant-free transmission resources between the two adjacent specific transmission time units, wherein a period of the specific transmission time unit in a time domain resource is Q transmission time units, wherein the specific transmission time unit is a transmission time unit in which a repeated transmission procedure is forcibly terminated, and Q is an integer greater than 2; determining, by the terminal device based on the determined transmission time unit and the parameter Q, a hybrid automatic repeat request HARQ process used to transmit the data packet; and when repeated transmission of the data packet is not terminated before the latter specific transmission time unit in the two adjacent specific transmission time units, performing, by the terminal device starting from the determined transmission unit by using the HARQ process, one transmission of the data packet in each transmission time unit in which a grant-free transmission resource is located until a transmission of the data packet is performed for the last time in the latter specific transmission unit.