An uplink control information sending method performed by a terminal device, the method comprising: receiving first downlink control information through a physical downlink control channel from a base station, wherein the first downlink control information is used to schedule an physical uplink shared channel, the first downlink control information comprises a first indication information and a second indication information, the first indication information indicates that the physical uplink shared channel is used to send uplink control information but is not used to send data and the second indication information indicates a modulation and coding scheme index of the physical uplink shared channel; determining, based on the first indication information, that the physical uplink shared channel is used to send uplink control information without data, determining, a first code rate of the physical uplink shared channel and a modulation order of the physical uplink shared channel based on the second indication information; and sending first uplink control information to the base station through the uplink shared channel, wherein the first uplink control information comprises a hybrid automatic repeat request-acknowledgement, wherein: a total quantity of resource elements in the physical uplink shared channel that are used to carry the first uplink control information is M, and a quantity of resource elements in the physical uplink shared channel that are used to carry the hybrid automatic repeat request-acknowledgement is a minimum value of a first quantity and the total quantity M, wherein the first quantity is equal to a round-up value of a ratio of a first product to a second product, wherein the first product is a product of a payload size of the hybrid automatic repeat request-acknowledgement and a code rate compensation parameter of the hybrid automatic repeat request-acknowledgement, and the second product is a product of the first code rate and the modulation order. receiving first downlink control information through a physical downlink control channel from a base station, wherein the first downlink control information is used to schedule an physical uplink shared channel, the first downlink control information comprises a first indication information and a second indication information, the first indication information indicates that the physical uplink shared channel is used to send uplink control information but is not used to send data and the second indication information indicates a modulation and coding scheme index of the physical uplink shared channel; determining, based on the first indication information, that the physical uplink shared channel is used to send uplink control information without data, determining, a first code rate of the physical uplink shared channel and a modulation order of the physical uplink shared channel based on the second indication information; and sending first uplink control information to the base station through the uplink shared channel, wherein the first uplink control information comprises a hybrid automatic repeat request-acknowledgement, wherein: a total quantity of resource elements in the physical uplink shared channel that are used to carry the first uplink control information is M, and a quantity of resource elements in the physical uplink shared channel that are used to carry the hybrid automatic repeat request-acknowledgement is a minimum value of a first quantity and the total quantity M, wherein the first quantity is equal to a round-up value of a ratio of a first product to a second product, wherein the first product is a product of a payload size of the hybrid automatic repeat request-acknowledgement and a code rate compensation parameter of the hybrid automatic repeat request-acknowledgement, and the second product is a product of the first code rate and the modulation order.