A control information sending method, comprising: receiving (Step 101, 201) at least one piece of control information sent by a device, wherein the at least one piece of control information carries hybrid automatic repeat request-acknowledgement codebook indication information, and the hybrid automatic repeat request-acknowledgement codebook indication information is used to indicate a hybrid automatic repeat request-acknowledgement codebook size; generating (Step 102, 202) a hybrid automatic repeat request-acknowledgement according to the hybrid automatic repeat request-acknowledgement codebook indication information; and sending (Step 103, 203) the hybrid automatic repeat request-acknowledgement to the device, wherein a bit quantity of the hybrid automatic repeat request-acknowledgement codebook indication information is N, a difference between hybrid automatic repeat request-acknowledgement codebook sizes corresponding to the hybrid automatic repeat request-acknowledgement codebook indication information is at least 2 N + 1, and N is a natural number greater than or equal to 2; and wherein the generating (Step 101, 202) a hybrid automatic repeat request-acknowledgement according to the hybrid automatic repeat request-acknowledgement codebook indication information comprises obtaining a set of hybrid automatic repeat request-acknowledgement codebook sizes corresponding to the hybrid automatic repeat request-acknowledgement codebook indication information in a state, and determining the hybrid automatic repeat request-acknowledgement codebook size according to the received downlink control information and the set of hybrid automatic repeat request-acknowledgement codebook sizes. receiving (Step 101, 201) at least one piece of control information sent by a device, wherein the at least one piece of control information carries hybrid automatic repeat request-acknowledgement codebook indication information, and the hybrid automatic repeat request-acknowledgement codebook indication information is used to indicate a hybrid automatic repeat request-acknowledgement codebook size; generating (Step 102, 202) a hybrid automatic repeat request-acknowledgement according to the hybrid automatic repeat request-acknowledgement codebook indication information; and sending (Step 103, 203) the hybrid automatic repeat request-acknowledgement to the device, wherein a bit quantity of the hybrid automatic repeat request-acknowledgement codebook indication information is N, a difference between hybrid automatic repeat request-acknowledgement codebook sizes corresponding to the hybrid automatic repeat request-acknowledgement codebook indication information is at least 2 N + 1, and N is a natural number greater than or equal to 2; and wherein the generating (Step 101, 202) a hybrid automatic repeat request-acknowledgement according to the hybrid automatic repeat request-acknowledgement codebook indication information comprises obtaining a set of hybrid automatic repeat request-acknowledgement codebook sizes corresponding to the hybrid automatic repeat request-acknowledgement codebook indication information in a state, and determining the hybrid automatic repeat request-acknowledgement codebook size according to the received downlink control information and the set of hybrid automatic repeat request-acknowledgement codebook sizes.