The utility model relates to a dynamic balance device of a coupling, in particular to a dynamic balance tool of the coupling and the components, which belongs to the mechanical structure technical field. The main points of the utility model are that a cylindrical core axle is suited with an inner cone sleeve, an outer cone sleeve is covered on the inner cone sleeve, and the utility model is characterized in that a thin wall circular ring is arranged at the tail part of the outer cone sleeve; two grooves are symmetrically arranged on the outer cone sleeve, and the grooves extend to the thin wall circular ring. The utility model has simple compact and reasonable structure; because the thin wall circular ring is arranged at the tail part of the outer cone sleeve and the grooves symmetrically arranged on the outer cone sleeve extend to the thin wall circular ring, the outer cone sleeve not only can uniformly expand in radial direction but also be as a whole; the utility model cam make a expanding sleeve uniformly expand, and eliminate the clearances between the cylindrical core axle and the expanding sleeve and the expanding sleeve and the components of the coupling; the centering accuracy is high, installation is convenient, the dynamic balance accuracy of the coupling can be improved, and the service life of the coupling and the safe operating cycle of the machine can be improved.