A control information sending method, wherein the method comprises: sending, by a network device (102, 300), first control information to a terminal device (116, 122, 400), wherein the first control information comprises first indication information and information about a first time-frequency resource, the first time-frequency resource carries at least first data, the first data comprises at least one first bit obtained by encoding a first information block, and the first indication information is used to indicate initial transmission or retransmission of the first information block; and sending, by the network device (102, 300), second control information to the terminal device (116, 122, 400), wherein the second control information comprises second indication information and information about a second time-frequency resource, the second time-frequency resource carries at least second data, the second data comprises at least one second bit obtained by encoding the first information block, and the second indication information is used to indicate that feedback information for the first information block is determined based on a result of combining and decoding the first data and the second data; characterized in that the second data is determined based on a third time-frequency resource, and the third time-frequency resource is a part of the first time-frequency resource, wherein the third time-frequency resource is a resource that reduces a probability that the terminal device (116, 122, 400) successfully decodes data carried on the third time-frequency resource; the at least one first bit obtained by encoding the first information block is stored in at least one buffer, and the second data is obtained from the at least one buffer based on a location of the third time-frequency resource in the first time-frequency resource and a mode of mapping, onto the first time-frequency resource, the at least one first bit obtained by encoding the first information block; and the method further comprises sending, by the network device (102, 300), fifth indication information to the terminal device (116, 122, 400), wherein the fifth indication information is used to indicate the third time-frequency resource. sending, by a network device (102, 300), first control information to a terminal device (116, 122, 400), wherein the first control information comprises first indication information and information about a first time-frequency resource, the first time-frequency resource carries at least first data, the first data comprises at least one first bit obtained by encoding a first information block, and the first indication information is used to indicate initial transmission or retransmission of the first information block; and sending, by the network device (102, 300), second control information to the terminal device (116, 122, 400), wherein the second control information comprises second indication information and information about a second time-frequency resource, the second time-frequency resource carries at least second data, the second data comprises at least one second bit obtained by encoding the first information block, and the second indication information is used to indicate that feedback information for the first information block is determined based on a result of combining and decoding the first data and the second data; characterized in that the second data is determined based on a third time-frequency resource, and the third time-frequency resource is a part of the first time-frequency resource, wherein the third time-frequency resource is a resource that reduces a probability that the terminal device (116, 122, 400) successfully decodes data carried on the third time-frequency resource; the at least one first bit obtained by encoding the first information block is stored in at least one buffer, and the second data is obtained from the at least one buffer based on a location of the third time-frequency resource in the first time-frequency resource and a mode of mapping, onto the first time-frequency resource, the at least one first bit obtained by encoding the first information block; and the method further comprises sending, by the network device (102, 300), fifth indication information to the terminal device (116, 122, 400), wherein the fifth indication information is used to indicate the third time-frequency resource.