Embodiments of the present application provide a signal sending method, a device, and a system. A base station modulates, by using a first modulation scheme, signaling carried in a control channel, and modulates, by using a second modulation scheme, data carried in a traffic channel; and the base station sends, to UE, a signal obtained after modulation. In this way, the base station can independently select a modulation scheme for the control channel and the traffic channel, avoiding a case in which a modulation scheme used by the control channel and a modulation scheme used by the traffic channel must be the same, so that the base station can flexibly select a channel modulation scheme.