Disclosed are methods and systems for determining, by a terminal device, downlink control information that includes a first information field and a second information field. The first information field is used to indicate whether to switch an active bandwidth part of a terminal device. When the first information field indicates to switch the active bandwidth part of the terminal device, the second information field is used to indicate one or more active bandwidth parts and frequency domain resource location of a data channel in the active bandwidth parts to switch; or when the first information field indicates not to switch the active bandwidth part of the terminal device, the second information field is used to indicate a frequency domain resource location of a data channel in a currently accessed active bandwidth part. A working bandwidth part of the terminal device can be indicated, and resource utilisation is improved.