In view of problems arising from the grid-connected wind turbine with the frequency converter, we propose a conceptual design of grid-connected wind turbine based on speed regulating differential mechanism (SRDM). The SRDM regulates its output speed and torque self-adaptively referring to wind rotor and makes the synchronous generator (SG) keep a constant speed to output electricity in steady frequency without the normal frequency converter and it has excellent low voltage ride through (LVRT). This paper offers the kinematics and dynamics analysis of the designed wind turbine and builds the SIMULINK model based on FAST (fatigue, aerodynamics, structures and turbulence) software. The simulation of speed, torque and power of wind rotor under average wind speed of 12 m/s and turbulence intensity of 20% can verify the feasibility of the designed wind turbine.