The present application provides a sidelink communication method and apparatus. The method includes: performing, by a terminal device, channel monitoring on shared spectrum; and if the result of the channel monitoring is that a channel is idle, starting, by the terminal device, transmission of a first sidelink channel at a first time domain position, where the first time domain position is one or more of the following: a time domain position indicated by first indication information; and a time domain position determined based on a first time unit, the first time unit being smaller than one slot.