The disclosure provides a rack, including nodes and power supplies, and a power controlling method thereof, including the following steps. Power information of each node is collected to calculate a total power consumption value of the nodes. A power supply enabling demand is calculated according to the total power consumption value and a maximum power supply value of the power supply. State information of each of the power supplies is read to obtain a first sequence of the power supplies. According to the power supply enabling demand and the first sequence, two of the power supplies are enabled and set as a master power supply and a secondary power supply, and the rest of the power supplies are disabled. While the master power supply provides a work voltage to the nodes, the secondary power supply does not supply the work voltage to the nodes.