A clasp assembly, which can be disconnected or connected with a watch chain quickly, includes a clasp cap, an inner bend plate, outer band plate, a screw, a rivet and an elastic shaft. The inner bend plate comprises an arc plate body and two cylindrical bodies, the two cylindrical bodies disposed on one end of the plate body, a thread hole provided on the surface of a distal end of each cylindrical body, a through hole provided on the other end of the plate body and a convex clasp provided on each side of the plate body. A groove is provided in the middle of the outer bend plate and a through hole is formed on one end of the out bend plate, which comprises two sections spaced by the groove, and linked with the through hole of the inner bend plate by engaging with the rivet pivotally. A through hole is formed on the other end of the outer bend plate which remains integral, and concave clasps are disposed symmetrically on the inner sides of the outer bend plate. The clasp cap is pivotally connected with the thread hole of the inner bend plate by the screw, through holes disposed in two side plates of the clasp cap. A hook clasp and a locking clasp for being connected with the watch chain are mounted on the elastic shaft engaging with the through holes, the locking clasp fitting into the hook clasp. A security cover is pivotally mounted on the rivet connecting the outer bend plate with the watch chain.