A multiphase control system is provided, which is adapted to convert power of an input power source into an output voltage for outputting through an output terminal. The multiphase control system comprises a plurality of control units connected in series to form a loop. Each of the control units receives a sequential input signal from an adjacent control unit connected there before through a multiphase input terminal, and generates a control signal to control power transmission from the input power source to the output terminal when determining that the output voltage is lower than a predetermined voltage value, and generates a sequential output signal at a multiphase output terminal for outputting to an adjacent control unit connected there after.