Abstract: After the accomplishment of those problems such as frequency conversion and speed regulation for power transfer, the asynchronous motor has shown great potential in the field of energy saving and will have a fast trend to development. By the cases of using the imported, S1MOVERT A frequency conversion unit and FUJI frequency converter, the author explains their effects of energy saving. The former is a transistor type for frequency conversion and speed regulation, which is suitable for the large sized oil transmission motor. The latter is a GTR type for pulse-amplitude modulation, which is suitable for the motor of medium and small sized wind blower and water pump.