A current balance circuit includes a first and a second current sensors, an averager, a first and a second control modules, and a first and a second rheostat elements. The first and second current sensors receive a first current and a second current from a power source respectively and convert the first and second currents into a first and a second voltages. The averager receives the first and second voltages and calculates to obtain an average voltage. The first and second control modules receive the first voltage, the second voltage, and the average voltage, to obtain a first and a second control signals, to control current conduction ability of the first and second rheostat elements, to make the first and second currents keep a dynamic balance.