The invention provides a compound bus bar, wherein the compound bus bar is composed of a plurality of flat-shaped bus bars in an overlapped mode. A plurality of extracted terminals are arranged on the compound bus bar. The plurality of extracted terminals serve as input or output interfaces and are connected with a main circuit. Transmission of energy is formed. The compound bus bar replaces a direct current bus in the prior art, is arranged in the flat shape, reduces parasitic inductance in the circuit and improves reliability of the circuit.