A power management system configured to supply electricity power to a plurality of power consumption devices, wherein the power management system comprises: a plurality of connection interfaces, configured to be respectively connected to one of the power consumption devices to perform signal transmission and power transmission; a system power supply, comprising a plurality of power supply units; wherein the system power supply is configured to supply electricity power to each of the connection interfaces, so as to supply electricity power to the power consumption devices through the connection interfaces; and a power management circuit, configured to be connected to each of the power consumption devices via each of the connection interfaces; wherein the power management circuit obtains a current total load of the power supply units, determines a target load of each of the power supply units wherein the target load is an optimal load of the power supply units to operate at an optimal work efficiency, and determines whether each of the connection interfaces is connected to one of the power consumption devices; and the power management circuit turns off power supply to the connection interface that is not connected to one of the power consumption devices, and determines an enabled number of the plurality of power supply units to be turned on according to the current total load and the target load of each of the power supply units, so that an current load of each of the power supply units to be turned on is close to the target load; wherein the power management circuit determines, through a status signal returned by a designated pin in each of the connection interfaces, whether each of the connection interfaces is connected to one of the plurality of power consumption devices. a plurality of connection interfaces, configured to be respectively connected to one of the power consumption devices to perform signal transmission and power transmission; a system power supply, comprising a plurality of power supply units; wherein the system power supply is configured to supply electricity power to each of the connection interfaces, so as to supply electricity power to the power consumption devices through the connection interfaces; and a power management circuit, configured to be connected to each of the power consumption devices via each of the connection interfaces; wherein the power management circuit obtains a current total load of the power supply units, determines a target load of each of the power supply units wherein the target load is an optimal load of the power supply units to operate at an optimal work efficiency, and determines whether each of the connection interfaces is connected to one of the power consumption devices; and the power management circuit turns off power supply to the connection interface that is not connected to one of the power consumption devices, and determines an enabled number of the plurality of power supply units to be turned on according to the current total load and the target load of each of the power supply units, so that an current load of each of the power supply units to be turned on is close to the target load; wherein the power management circuit determines, through a status signal returned by a designated pin in each of the connection interfaces, whether each of the connection interfaces is connected to one of the plurality of power consumption devices.