A feedback information sending method and an apparatus are provided. A first communications apparatus may determine sidelink feedback information, and send a reference signal to a second communications apparatus, where the reference signal carries the sidelink feedback information. In this way, terminals can send and receive the sidelink feedback information by using the reference signal, to improve transmission efficiency of the sidelink feedback information. When the terminal needs to send both a control channel or a data channel and feedback information in a same slot, this method avoids a problem that the terminal needs to simultaneously send two channels, e.g., the control channel (or the data channel) and a feedback channel, avoids reducing original transmission efficiency of the control channel or the data channel, and implements compatibility between sending through the control channel (or the data channel) and feedback through the feedback channel.