This application provides an information transmission method, an apparatus, and a system, to improve coverage and transmission reliability that are of uplink control information UCI, thereby improving communication efficiency. In the method, after determining UCI, a terminal device sends the uplink control information on N frequency domain resource units, where N is a positive integer greater than 1. Based on this solution, when a power spectral density is determined, a larger quantity of frequency domain resource units may indicate a higher transmit power, so that coverage of the UCI can be increased. In addition, when a quantity of bits of the UCI is small, rate matching may be performed on the N frequency domain resource units, to reduce a code rate, so that transmission reliability is improved.