A communication method, apparatus, and system are provided, to decrease a degree of sensitivity degradation and reduce impact of the sensitivity degradation on network coverage performance. In the method, a network device sends first configuration information to a terminal device. When the first configuration information indicates that the terminal device is allowed to reduce a transmit power, the terminal device reduces the transmit power based on a power adjustment factor if a difference between reference sensitivity of a first power class and reference sensitivity of a second power class is greater than or equal to a first threshold in configured channel bandwidth. Before the transmit power is reduced, a power class of the terminal device is the first power class. The second power class is lower than the first power class.