Disclosed is a method for transmitting Uplink Control Information. The method includes: determining, by a terminal device, a set of uplink control channel resources according to the first number of bits, the first number of bits being determined according to high-level parameters; receiving configuration information sent by a network device, the configuration information indicating an uplink control channel resource in the set of uplink control channel resources; determining first UCI to be transmitted according to a channel format corresponding to the uplink control channel resource, the number of bits occupied by the first UCI being less than or equal to the first number of bits; and transmitting the first UCI in the uplink control channel resource using the channel format. Therefore, the terminal device determines the UCI to be transmitted based on the channel format corresponding to the uplink control channel resource.