Balance device used for electric spindle

The invention relates to a balance device used for an electric spindle. The balance device is mainly composed of a balance block, a fixed cover, a rotating disc and fixed discs. The fixed discs are symmetrically mounted at the positions, on the two sides of a rotor, of the spindle and can rotate along with the spindle. Circumferential sliding ways are arranged on the fixed discs. The rotating discand the fixed discs are axially fixed by bolts and nuts. The rotating disc and the fixed discs can relatively rotate along the circumferential sliding ways by loosening the nuts, and the circumferential angle can be adjusted. Radial sliding ways and a radial convex edge are arranged on the rotating disc. A radial groove is formed in the balance block and can cooperate with the radial convex edge,and a guide function is achieved. The balance block can be connected with the rotating disc through the fixed cover, and the fixed cover is provided with a convex edge to cooperate with a groove in the other side of the balan