Embodiments of the present invention provide a method, device, and system for acquiring a shared power, which relate to the field of communications and can increase a utilization rate of power resources and reduce a waste of power resources. The method includes: acquiring, by a network side device, transmit powers of all carriers in a first cell; adjusting, by the network side device, a carrier with a maximum transmit power in unadjusted carriers in all the carriers onto a power amplifier with a maximum available power in all power amplifiers of the first cell; updating, by the network side device, an available power of the power amplifier with a maximum available power; repeatedly executing, by the network side device, the adjusting and updating steps until adjustments to all the carriers are complete; and acquiring, by the network side device, a minimum value in values of available powers of all the power amplifiers as a sharable power of the first cell. The method, device, and system for acquiring a shared power provided by the embodiments of the present invention are used for power sharing.