A method for repeated transmission, comprising: determining (S301) , 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 (S302), 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 (S303) , 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 (S301) , 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 (S302), 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 (S303) , 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. <EOS>