A method for sending control information, wherein the method comprises: determining, by a terminal device based on a relationship between a first time length and a second time length, an uplink control channel for carrying control information, wherein the uplink control channel for carrying control information is a first uplink control channel or a second uplink control channel, the first time length is a time unit including one or more symbols corresponding to the first uplink control channel, the second time length is a time unit including one or more symbols corresponding to the second uplink control channel, the first uplink control channel is used to carry a hybrid automatic repeat request-acknowledgement, HARQ-ACK, message, and the second uplink control channel is used to carry a scheduling request, SR; and sending, by the terminal device, at least the HARQ-ACK message on the first or second uplink control channel for carrying control information, wherein the determining, by a terminal device based on a relationship between a first time length and a second time length, an uplink control channel for carrying control information comprises: when the first time length is equal to the second time length, determining, by the terminal device, that the uplink control channel for carrying control information is the second uplink control channel, or when the first time length is unequal to the second time length, determining, by the terminal device, that the uplink control channel for carrying control information is the first uplink control channel. determining, by a terminal device based on a relationship between a first time length and a second time length, an uplink control channel for carrying control information, wherein the uplink control channel for carrying control information is a first uplink control channel or a second uplink control channel, the first time length is a time unit including one or more symbols corresponding to the first uplink control channel, the second time length is a time unit including one or more symbols corresponding to the second uplink control channel, the first uplink control channel is used to carry a hybrid automatic repeat request-acknowledgement, HARQ-ACK, message, and the second uplink control channel is used to carry a scheduling request, SR; and sending, by the terminal device, at least the HARQ-ACK message on the first or second uplink control channel for carrying control information, wherein the determining, by a terminal device based on a relationship between a first time length and a second time length, an uplink control channel for carrying control information comprises: when the first time length is equal to the second time length, determining, by the terminal device, that the uplink control channel for carrying control information is the second uplink control channel, or when the first time length is unequal to the second time length, determining, by the terminal device, that the uplink control channel for carrying control information is the first uplink control channel. when the first time length is equal to the second time length, determining, by the terminal device, that the uplink control channel for carrying control information is the second uplink control channel, or when the first time length is unequal to the second time length, determining, by the terminal device, that the uplink control channel for carrying control information is the first uplink control channel.