Large-scale wind turbines have become the trend of the wind power industry. However, the main factors restricting the large scale wind turbines are frequent replacement of carbon brush and slip ring and the harmonic of the stator current in double-fed induction generator, plus converters' large volume, high cost, and high failure rate in full power converter of wind turbine. Therefore, new double rotor speed-regulating wind power generation system comprising a double rotor speed-regulating device connected to the gearbox and the synchronous generator is proposed for the sake of lower cost, higher reliability, and stronger adaptability of the power grid. The structure of the system and the connection of each component are described; meanwhile, the working principle of the system under different operating conditions is analyzed. Furthermore, the mathematical model of the system is established, besides the control strategy being proposed. The simulation results verify the correctness of the mathematical model and the control strategy.