A voltage balance control method for controlling a flying-capacitor multilevel converter, the flying-capacitor multilevel converter comprising a plurality of flying-capacitor multilevel branch circuits connected in parallel, each of the plurality of flying-capacitor multilevel branch circuits comprising at least one flying capacitor (C1, C2), an even number of switches (Q1, Q2, Q1b, Q2b) and an output inductor (Lf), and each of the plurality of flying-capacitor multilevel branch circuits having an output inductor current flowing through the output inductor (Lf), wherein the voltage balance control method comprises steps of: (a) generating an even number of control signals to control the even number of switches (Q1, Q2, Q1b, Q2b) of each of the plurality of flying-capacitor multilevel branch circuits correspondingly; (b) judging whether a voltage on each of the at least one flying capacitor (C1, C2) satisfies a preset condition, wherein if the voltage on each of the at least one flying capacitor (C1, C2) satisfies the preset condition, then jumping to step (e), and if the voltage on each of the at least one flying capacitor (C1, C2) does not satisfy the preset condition, then jumping to step (c); (c) judging whether an amplitude of a resultant current representing the sum of the output inductor current of the plurality of flying-capacitor multilevel branch circuits is lower than or equal to a threshold current value, wherein if the amplitude of the resultant current is lower than or equal to the threshold current value, then jumping to step (d), and if the amplitude of the resultant current is higher than the threshold current value, then jumping to step (e); (d) controlling a flowing direction of the output inductor current of at least one of the plurality of flying-capacitor multilevel branch circuits to be opposite to a flowing direction of the resultant current by controlling the even number of switches (Q1, Q2, Q1b, Q2b) of each of the plurality of flying-capacitor multilevel branch circuits; and (e) controlling the voltage on each of the at least one flying capacitor (C1, C2) to be equal to a voltage reference according to the output inductor current of each of the plurality of flying-capacitor multilevel branch circuits by controlling the even number of switches (Q1, Q2, Q1b, Q2b) of each of the plurality of flying-capacitor multilevel branch circuits, and then performing the step (b) again. (a) generating an even number of control signals to control the even number of switches (Q1, Q2, Q1b, Q2b) of each of the plurality of flying-capacitor multilevel branch circuits correspondingly; (b) judging whether a voltage on each of the at least one flying capacitor (C1, C2) satisfies a preset condition, wherein if the voltage on each of the at least one flying capacitor (C1, C2) satisfies the preset condition, then jumping to step (e), and if the voltage on each of the at least one flying capacitor (C1, C2) does not satisfy the preset condition, then jumping to step (c); (c) judging whether an amplitude of a resultant current representing the sum of the output inductor current of the plurality of flying-capacitor multilevel branch circuits is lower than or equal to a threshold current value, wherein if the amplitude of the resultant current is lower than or equal to the threshold current value, then jumping to step (d), and if the amplitude of the resultant current is higher than the threshold current value, then jumping to step (e); (d) controlling a flowing direction of the output inductor current of at least one of the plurality of flying-capacitor multilevel branch circuits to be opposite to a flowing direction of the resultant current by controlling the even number of switches (Q1, Q2, Q1b, Q2b) of each of the plurality of flying-capacitor multilevel branch circuits; and (e) controlling the voltage on each of the at least one flying capacitor (C1, C2) to be equal to a voltage reference according to the output inductor current of each of the plurality of flying-capacitor multilevel branch circuits by controlling the even number of switches (Q1, Q2, Q1b, Q2b) of each of the plurality of flying-capacitor multilevel branch circuits, and then performing the step (b) again.