A system and method for transmitting a reference signal in a cell that uses an unlicensed frequency band. The method includes determining a candidate resource set that is used when a first reference signal is transmitted in the cell that uses the unlicensed frequency band, where the candidate resource set includes a preset resource and at least one flexible candidate resource, determining a first candidate resource that is used when the first reference signal is transmitted in the cell that uses the unlicensed frequency band, where a channel on the unlicensed frequency band corresponding to the first candidate resource is in an idle state, and the first candidate resource is the preset resource or a flexible candidate resource in the candidate resource set, and sending the first reference signal on the first candidate resource.