The invention relates to the field of casting section equipment of wear resistant media for ball mills, in particular to a large-size water-cooling metal casting section mechanism which comprises a die body, a supporting seat which is connected with rotating shafts of the die body in a rotating way, a water inlet pipe and a water outlet pipe which are communicated with an inner cavity of the die body, and a hanging hook of a casting ladle. The invention is characterized in that the die body comprises a die cylinder with a hollow cavity, as well as a hollow rotating shaft I and a hollow rotating shaft II which are respectively connected with the end part of the die cylinder fixedly; the hollow rotating shaft I is connected with a driving device; the water inlet pipe arranged in a hole of the hollow rotating shaft I and the water outlet pipe arranged in a hole of the hollow rotating shaft II are respectively communicated with the inner cavity of the die body; the water outlet pipe is ina bent pipe structure; the water inlet end is positioned at the upper part of the inner cavity of the die body; the casing ladle is hung on the hanging hook of flexible connection above the die body;a heat insulating kiln is arranged below the die body; and the driving device uses an infinite variable speed motor. The invention has the advantages of time saving, labor saving and high product hardness, and the working efficiency is increased by 60%.