The present application provides a method and apparatus for configuring a transmission bandwidth, and a device, for accelerating an activation speed of a carrier/BWP, reducing waiting time of a UE, and saving power consumption of the UE. The method comprises: determining a first carrier/first BWP; and sending a PDCCH to a user terminal UE by means of a second carrier/second BWP, the PDCCH being used for bearing instruction information for activating the first carrier/first BWP and sending a reference signal over the first carrier/first BWP, so that the UE may activate the first carrier/first BWP and receive the reference signal, and the reference signal is used by the UE for performing channel measurement and synchronous tracking on the first carrier/first BWP.