The present disclosure discloses a method and system for reducing a circulating current between a plurality of non-isolated modules operating in parallel. The input terminals and the output terminals of the plurality of non-isolated modules are respectively connected in parallel, and each of the non-isolated modules comprises a first stage converter, a bus capacitor and a second stage converter, which are electrically connected in sequence. For each of the non-isolated modules, the method comprises: comparing a first signal reflecting the input power of the non-isolated module with a reference value to obtain a comparison result; and adjusting the voltage of the bus capacitor according to the comparison result, wherein the voltage of the bus capacitor is decreased when the first signal is greater than the reference value, and the voltage of the bus capacitor is increased when the first signal is less than the reference value.