A big wind wheel single-grade gear generator is disclosed, which is characterized in that a main shaft 1 is tightened on a tower head 2 for centering action of a wind wheel only, the wind wheel adopts a hub 3 and a wheel support 4 to connect as an integral for supporting an inner vane 11 and an outer vane 12 to approach external diameter of big circumference as near as possible in order to improve the speed and efficiency of the vane tip. Simultaneously, the segment is an axial inner vane 11 and outer vane 12, which not only reaches the goal of hyper-big wind wheel, but also shortens the vanelength and reduces bending torque and vane weight. The wheel support 4 can be an inner ring which is provided with a gear coil 5 and big gear kinetic energy output device of the external ring 7, which separately gear small gear of a motor M1 and a motor M2 to generate. The big wind wheel single-grade gear generator has the advantages of that firstly saving a verbose drive chain and energy consumption of the prior technique, secondly being beneficial to break through bottleneck of the hyper big wind wheel.