A signal transmission method and apparatus are provided. The signal transmission method provided in embodiments of the present invention includes: determining a modulation type of service data that needs to be transmitted, where the modulation type includes hierarchical modulation and non-hierarchical modulation; modulating, by means of the hierarchical modulation when it is determined that the modulation type is the hierarchical modulation, the service data that needs to be transmitted, and sending a modulated hierarchical modulation signal to UE; and sending modulation configuration information to the UE, where the modulation configuration information includes information used to indicate the modulation type. By using the embodiments of the present invention, the system spectrum utilization efficiency and the system throughput can be greatly improved.