The invention discloses a feeding device and a feeding method for a cadmium-removing boiling purification tank system, which are applied to a series cadmium-removing boiling purification tank system. The device comprises a zinc powder pulping device, a liquid seal device and a zinc powder pulp distributor, wherein the zinc powder pulping device, the liquid seal device and the zinc powder pulp distributor are overlapped up and down vertically and connected in a sealed manner with the inner cavities communicated; the liquid seal device has an overflowing exhaust opening; the lower part of the liquid seal device is communicated with a bottom flow pipe of a hydrocyclone; and the zinc powder pulp distributor is provided with a zinc powder pulp outlet pipe which is matched and connected with all cadmium-removing boiling purification tanks in the system. The method comprises: filling zinc powder in the zinc powder pulping device; allowing the overflowing material of the hydrocyclone to pulp the zinc powder initially and allowing the zinc powder pulp to flow into the liquid seal device to be mixed with the bottom flow of the hydrocyclone, clarifying the mixture; and allowing the zinc powder pulp from the liquid seal device to flow into the zinc powder pulp distributor, removing cadmium, allowing the zinc powder pulp to flow to the bottom of the cadmium-removing boiling purification tanks together with zinc sulfate solution and completing feeding. In the invention, closed feeding is realized, air is prevented from entering the cadmium-removing boiling purification tanks during feeding, and the device has the advantages of simple structure and convenience for operation.