Provided in the embodiments of the present application are a signal transmission method and device, the method comprising: a first device determines a target channel access mechanism from at least two channel access mechanisms, the at least two channel access mechanisms being candidate channel access mechanisms for the first device to transmit first signals on an unlicensed carrier; on the basis of the target channel access mechanism, the first device performs channel sensing of the unlicensed carrier in order to determine whether time frequency resources used by the first device for sending the first signals are available, the first signals comprising at least two reference signals, the at least two reference signals comprising a first reference signal and a second reference signal, and the first reference signal being positioned before the second reference signal on the time domain.