Embodiments of this application provide a signal transmission method and apparatus. The method includes: receiving, by a terminal device, configuration information sent by a network device, where the configuration information is used to instruct the terminal device to send a reference signal, and a resource used to transmit the reference signal is determined based on a public cell identity of a cell to which the terminal device belongs; and sending, by the terminal device, the reference signal based on the configuration information by using the resource. According to the signal transmission method and apparatus in the embodiments of this application, an existing reference signal can be used to perform interference/channel measurement between terminal devices, so that a terminal device on a receiving side can distinguish between interference cells while reference signal utilization is improved.