Combined dumbbell barbell

The combined dumbbell barbell comprises barbell rods, dumbbell rods, dumbbell pieces, mounting parts, connecting mechanisms and limiting fixing parts, the two ends of the barbell rods and the dumbbell rods form connecting structures through the connecting mechanisms correspondingly, and each dumbbell rod comprises a dumbbell rod body and a holding sleeve; circumferential grooves extending in the circumferential direction of the dumbbell rod body are formed in the outer walls of the left end and the right end of the dumbbell rod body, and axial grooves extending in the axial direction of the dumbbell rod body are further formed in the outer walls of the dumbbell rod body; the connecting mechanism comprises a first connecting piece, a second connecting piece and a clamping ring, a first built-in thread is arranged on the inner side of the end, close to the barbell rod, of the first connecting piece, a second built-in thread is arranged on the inner side of the end, close to the dumbbell rod, of the second conne