The invention belongs to the field of civil engineering, and relates to a fabricated shear-wall energy-dissipation vibration-reduction horizontal connecting device and a construction method thereof. A pre-embedded part and a connecting part of the fabricated shear-wall energy-dissipation vibration-reduction horizontal connecting device are both arranged in the wall body, changes of performances such as corrosion, erosion and aging can be avoided, the durability of the whole structure is ensured, plane outer warping of an energy-dissipation connecting device is avoided, and the better energy-dissipating capacity can be achieved. The energy-dissipation connecting part is placed in the wall body and coincides with the axis of a horizontal shaft of the section of the wall body, force balance of the wall body, rigidity in the plane and carrying capacity are ensured, and eccentric bending moment can not be generated. With the connecting mode, the efficiency of prefabricated shear-wall on-site assembling construction can be improved substantially, enough initial rigidity supplied to shear-wall to connect under the function of small vibration can be achieved, under the function of big vibration, earthquake energy can be dissipated, and vibration-reduction thoughts of structure and component ductility can be improved, and meanwhile, the whole effect of building beauty and space usage can not be influenced, steel products can be saved, and a certain economic benefit can be achieved.