In order to improve cooling and lubrication effect of little quantity lubrication, air jet assisted little quantity lubrication (AJLQL) was put forward and milling experiment of aviation aluminum alloy 7050T7451 was carried out by using AJLQL system. A comparative study of dry cutting, AJLQL cutting and flood lubrication cutting was conducted based on cutting force signals. The results show that the cutting force under dry cutting condition is larger than that of AJLQL cutting. With the increase of cutting fluid flow rate, the lubricating ability of airliquid two phase coolinglubrication medium increases, which results in the decrease of cutting force. Comparison of cutting force between AJLQL cutting and flood lubrication cutting shows that the cutting force of AJLQL cutting is smaller than that of flood lubrication cutting, which indicates that the lubrication effect of AJLQL is better than that of flood lubrication, but the cutting fluid usage is only 3% of the latter.