A vacuum smelting device with mold-temperature control design includes: a chamber body and a cabin door, wherein the chamber body and the cabin door form a vacuum closed space; a smelting crucible disposed in the vacuum closed space for smelting raw materials to a molten metal; a casting mold also disposed in the vacuum closed space for accommodating the molten metal poured from the smelting crucible, and solidifying the molten metal to an as-cast alloy; and a mold-temperature control module surrounding the casting mold for controlling the temperature of the casting mold.