The present involves magnetic scrubber assembly and its design method for cleaning the wall-glass of an aquarium, the center of gravity of the internal scrubbing component is designed underneath its the geometrically horizontal central axes the product of the length Lp from the center of gravity Pp of internal scrubbing component to the lowest part and the gravity P of the internal scrubbing component is smaller than the product of the length Lf from equivalent function point Pf of buoyancy F that the internal scrubbing component is received to its lowest part and the buoyancy F that the internal scrubbing component is received, therefore, which can ensure that the internal scrubbing component can erect automatically after it lied down for whatever reasons. When the internal scrubbing component breaks away from the control of hand-hold scrubbing component, the internal scrubbing component can sink upright, and the magnetic scrubber assembly can be conveniently restored to the normal operation condition.
