MQL technique has been recognized as the most representative method of environmentally friendly near-dry machining. In machining of aluminum and its alloys, since they have highly adhesive characteristics, effective lubrication is often necessary and MQL machining sometimes finds difficulty. This paper therefore investigates the lubricating action of MQL media with various compositions in machining of aluminum. Detailed examination regarding the contents of carrier gases has demonstrated oxygen leads to the low cutting performance and its concentration in carrier gases has to be kept below the level between 1% and 10% to attain successful MQL machining of aluminum. Further, increasing the amount of MQL lubricant supply by boosting the air pressure is the efficient and convenient way to make MQL drilling of aluminum satisfactory.