A control information sending/receiving method and device are provided, to implement indicating a time-frequency location of a control channel to a terminal device in a 5G NR system or a future evolved LTE system. The method includes: receiving, by a terminal device, broadcast information; determining, from at least two predefined time-domain locations, a time-domain location of a broadcast channel carrying the broadcast information; determining a time-domain location of a control channel based on the time-domain location of the broadcast channel; and performing control channel detection in the determined time-domain location of the control channel.