Embodiments of this application provide a signal transmission method and a communication apparatus in a multi-waveform scenario, and are applied to a scenario in which a single-carrier waveform and a multi-carrier waveform coexist. In this method, a network device indicates, via first indication information, a terminal device to transmit a signal by using transmission parameters corresponding to the first indication information, so that the terminal device transmits the signal by using the specified transmission parameters. Transmission parameters includes at least two of a transmission bandwidth, an extended bandwidth, or a total bandwidth. According to the embodiments of this application, a transmit end may perform sending by using the single-carrier waveform, and a receive end may perform receiving by using the multi-carrier waveform; or a transmit end may perform sending by using the multi-carrier waveform, and a receive end may perform receiving by using the single-carrier waveform.