This application provides a communication method, a communications apparatus, and a communications system. The method includes: receiving first indication information, where the first indication information indicates at least two first parameters, and the at least two first parameters are used for determining at least one of an uplink data channel power, an uplink control channel power, or an uplink reference signal power during dynamic scheduling; and determining a second parameter obtained when a first time element is not used to transmit at least one of an uplink data channel, an uplink control channel, or an uplink reference signal, where the second parameter is at least one of a nominal power, a path loss adjustment factor, a path loss, or a closed-loop power control adjustment value. The method is applicable to power control and/or power headroom reporting in a multi-beam system.