Mine-used centrifuge is a typical multi (bi)-rotor system. Obvious problem that occurs during the use of multi-rotor system is intense vibration caused by imbalance of each rotor. How to separate imbalance amount of each rotor from complicated beat vibration signal is nodus of dynamic balance of this kind of rotor system. The paper adopts set average technology that is deducing average segment date according to common multiple, realizes abstracting each imbalance signal from every rotor, balances every rotor one by one, which lead to balance of engine set at last.[Descriptors] Mine-used centrifuge Multi-rotor Dynamic balance Common multiple Mine-used centrifuge is a typical multi (bi) -rotor system. Obvious problem that occurs during the use of multi-rotor system is intense vibration caused by imbalance of each rotor. is nodus of dynamic balance of this kind of rotor system. The paper adopts set average technology that is deducing average segment date according to common multiple, realizes abstracting each imbalance signal from every rotor, balances every rotor one by one, which lead to balance of engine set at last. [Descriptors] Mine-used centrifuge Multi-rotor Dynamic balance Common multiple