The invention discloses a metal plate rust removing device. The metal plate rust removing device comprises a rust removing box and circulating pipes. The rust removing box comprises a box body and a box cover. The bottom of the box body is supported by a supporting frame. An electrolysis sleeving plate is further fixedly installed between the box body and the box cover. A cathode plate and an anode plate are installed at the two ends of the bottom of the electrolysis sleeving plate separately. An electrolysis inserting plate box is fixedly installed at the bottom of the anode plate. A circulating pump is further arranged between the cathode plate and the electrolysis inserting plate box. The circulating pipes are connected through a direct flow tube. The circulating pipes are both fixedly provided with flow regulating valves. Joint pins are fixedly installed at the two ends of the direct flow tube correspondingly. Sealing valves are fixedly installed inside the corresponding joint pins, and the center of the direct flow tube is also fixedly provided with a flow regulating valve. Flow limiting valves are further fixedly installed at the two sides of the flow regulating valve, and a plurality of metal plates can be electrolyzed at the same time. The actual rust removing efficiency can be greatly improved, rust removing efficiency is high, pollution can be avoided, the effect of being not prone to rusting once again is achieved, operation is easy, more time and labor are saved, and the practicability is higher.