The present disclosure relates to the field of mobile communications technologies, and in particular, to a signal transmission method and an apparatus. In the signal transmission method, user equipment receives, from a base station, first information in a physical downlink control channel, where the first information is used for determining precoding information of a sounding reference signal (SRS). The user equipment determines precoding information of the SRS based on the first information. The user equipment performs, based on the precoding information, precoding on the SRS to generate a precoded signal, and sends the precoded signal to the base station.