The utility model relates to a clamping device for a grinding wheel axle. The clamping device comprises an upper clamping part, a lower clamping part, a bolt and a nut, wherein, the bolt and the nut are fixed on the clamping parts in a penetrating manner; the lower clamping part takes the shape of a single-piece metal musical instrument named cymbal; a hole is formed in the middle of the cymbal-shaped body; the bolt penetrates through the hole on the lower clamping part; the bolt and the nut are fixedly screwed on the outer surface and the inner surface of the lower clamping part; the upper clamping part adopts a bell jar-shaped structure; a penetration hole is formed at the top part of the upper clamping part; a nut is arranged on the outer surface of the penetration hole; and the upper part of the bolt fixedly screwed on the lower clamping part penetrates through the penetration hole of the upper clamping part, and is fixedly screwed on the outer surface of the upper clamping part together with the nut of the upper clamping part. The utility model has the advantages that the processing and production efficiency of grinding wheels is improved; the pressure of the clamping device acted on a grinding wheel axle is uniform; the quality of grinding wheels produced through the clamping device is stable; and the phenomenon in the prior art that the clamping device cannot be screwed tightly is eliminated.