Abstract: A spindle structure of a motor rotor is disclosed. An insulating layer is integrally formed between the spindle and the silicon steel pieces of the motor by injection. Two sun plates are integrally formed at the insulating layer and clamp the two ends of the silicon steel pieces. Trenches are formed on the spindle. In the each of the positions that the insulating layer is connected to the sun plates, a rib with a predetermined height is integrally formed for enhancing the stability of the center of gravitation and the magnetic flux, and for enhancing the connection between the spindle, silicon steel pieces and the sun plates. Furthermore, two ladder shape buckling portions are formed at the insulating layer and outside the sun plates for positioning a fan.