The utility model discloses a multi-isolation-transformer device for an electrolytic crown block. The multi-isolation-transformer device comprises an isolation transformer for an aluminum output trolley, an isolation transformer for a fixed hoist, a general isolation separation for a tool trolley and second-layer isolation transformers on the tool trolley, wherein the second-layer isolation transformers comprise an isolation transformer for a hydraulic station, an isolation transformer for a slag removing discharging pipe and an isolation transformer for a cab rotating motor, and the isolation transformer for the aluminum output trolley, the isolation transformer for the fixed hoist, the general isolation separation for the tool trolley and the second-layer isolation transformers on the tool trolley are arranged corresponding to operating mechanisms and insulation levels of the electrolytic crown block. According to the multi-isolation-transformer device, the alternating-current and direct-current cross risk between electric equipment and operating mechanism electric motors making contact with a direct-current power source (an electrolytic cell) is better reduced, and the loss can be reduced to the minimum. Meanwhile, convenience can be brought to detection of electric leakage and insulation damage of the electric equipment in a layering mode, and the multi-isolation-transformer device can be widely applied to the electric equipment with the alternating-current and direct-current cross risk and multi-layer insulation or the electric equipment with various insulation mechanisms.