The embodiments of this application provide a method and a device for sending and receiving control information, to flexibly adjust reliability of uplink transmission. A network device sends indication information of an uplink control channel to a terminal device. The indication information of the uplink control channel indicates at least one parameter of the following transmission parameters: a time domain length, a frequency domain length, a time domain repeat count, a frequency domain repeat count, or a transmit diversity manner. The network device receives uplink control information from the terminal device according to the indication information by using the uplink control channel.