A communications method and apparatus are provided. The method includes: receiving first configuration information, where the first configuration information is used to configure a first bandwidth part (BWP); and sending sidelink data on a resource included in a first transmission resource pool, where a frequency range of the first transmission resource pool is included in a frequency range of the first BWP and a frequency range of a second BWP, and the second BWP is an activated uplink BWP. The communications method and apparatus in this application can implement terminal device communication on the first BWP and the second BWP, and reduce a time of switching between the first BWP and the second BWP, thereby improving efficiency of the communication on the first BWP and the second BWP.