The degassing and purification technology of molten aluminum alloys by rotary impeller is investigated, aimed at the existent problems in the aspect of the degassing and purification technology of molten aluminum alloys. All parts of the equipment are analyzed and designed. Especially, in the design of spinning rotor, a special pipeline is fixed inside the rotate pole, in order to decrease the temperature inside the rotate pole and prevent the spray flux softening owing to the high temperature and spinning rotor jamming. In the pneumatic system of the equipment, gas-in part and adjustment part are designed respectively. The flux can be altered continually, which can increase the flux, but not cause the molten aluminum alloys surge with the same rotate speed. Advanced controlling schemes for the equipment are investigated in the view of hardware and software. In hardware, the theory and methods to use Siemens PLC for control system are analyzed and designed. In software, the control software is programmed in STEP7. At the same time, the safety and steady of the equipment are fully considered. The manual control and Auto-control model are designed, and the emergencies stop is set in Auto-control model to avoid the problems worsen in emergency.