The invention discloses a movable negative-pressure dust collecting and purifying system for an aluminum electrolysis multifunctional unit, and belongs to the technical field of non-ferrous metallurgical environmental protection. The movable negative-pressure dust collecting and purifying system for the aluminum electrolysis multifunctional unit comprises a negative-pressure dust collecting deviceand a dry-process purifying device, wherein the negative-pressure dust collecting device comprises a side telescopic structure and a top sealing structure; the side telescopic structure comprises a flexible side part outer cover, upper and lower telescopic brackets and an electric-control lifter; the top sealing structure comprises a flexible top outer cover, a slide framework, a collecting smoketube and a bottom wheel group; the dry-process purifying device comprises a fresh aluminum oxide box, a filter barrel type dust collector and a fluoride supported aluminum oxide box which are sequentially connected; and the filter barrel type dust collector communicates with the collecting smoke tube through an inlet flue. The movable negative-pressure dust collecting and purifying system for thealuminum electrolysis multifunctional unit is simple in structure, is low in operation cost, effectively collects unorganized smoke gas while an aluminum electrolysis cell performs pole changing operation and aluminum discharging operation, and reduces unorganized emission of electrolysis smoke gas.