This paper is mainly to design the small wind turbine blades to make the wind turbines have automatic braking ability. This study has two main aspects, including choosing the reinforced materials and designing the structure of the blades. According to the fiber hybrid principle, carbon fibers are employed in the main stress area of the blades and other area using glass fiber. At the same time, Aramid fibers are mixed in every area of the blade in order to enhance the tenacity of the blade. The other work is designing the structure of the blade with big main body and small abdomen which twists easily. At the designed wind speed, the power output reaches its rated capacity. Above this wind speed, turbine blades twist to adapt to wind speed and make the rotor solidity of wind turbine declined. While the wind speed changes and becomes small, the torsion of wind turbines’ blades turns back. Thus the wind turbines’ rotor solidity becomes greater and power output increases. So at a certain speed ( 36m/s), the wind turbine can adjusts itself to control the power output keeps on a certain level. And then it brakes by itself.