The invention discloses a high permeability new energy power grid connection system and stability control method which belongs to the field of a new energy power system. When new energy has high permeability (50% to 100%), a power grid connection system is composed of a prime mover, a motor and a synchronous generator, or is composed of a motor and a synchronous generator. Rotors of the units are coaxially connected. New energy power is transmitted and converted to power the motor. According to the invention, the method is different from a traditional new energy direct grid connection method; a high permeability new energy power system has enough inertia; the frequency stability of the system is improved; the synchronous generator is retained to effectively damp system oscillation; through voltage and reactive power control, the power angle and the voltage stability of the system are improved; the peaking capacity of traditional thermal power and hydropower units and the like is retained; and through coordinated control of the motor, the synchronous generator and the prime mover, the dynamic regulation characteristic of the system is improved.