Various purification methods were explored to eliminate the dissolved hydrogen and nonmetallic inclusious from molten alu minum alloys. A novel rotating impeller head with self-oscillation nozzles or an electromagnetic valve in the gas circuit was used to produce pulse gas currents for the rotary impeller degassing method. Water si mulation results show that the size of gas bubbles can be decreased by 10%-20% as compared with the constant gas current mode. By coating ceramic filters or particles with active flux or enamels, composite filters were used to filter the scrap A356 alloy and pure alu minum. Experimental results de monstrate that better filtration efficiency and operation performance can be obtained. Based on nu merical calculations, the separation efficiency of inclusions by high frequency magnetic field can be significantly improved by using a hollow cylinder like separator or utilizing the effects of secondary flow of the melt in a square separa-tor. A multi-stage and multi-media purification platform based on these methods was designed and applied in on-line pro- cessing of molten aluminum alloys. Mechanical properties of the processed scrap A356 alloy are greatly improved by the composite purification.