The ionized air assisted cutting is one of green cutting modes, and the air jet treated by corona discharge is injected to the cutting zone and plays a lubricating and cooling effect. The changes on machine structure are not necessary in the application of ionized air assisted cutting. In the cutting of difficult-to-cut materials, the technology is close or superior to traditional cutting fluids on processing efficiency, processing quality, tool life, low cost etc., almost no environmental pollution and health hazards, and is a kind of cutting technology owning broad prospect.A series of basic theoretical and experimental study on the principles and characteristics of atmospheric pressure gas discharge was carried out using self-designed ionized air generating device. The effects of the ionized air in the cutting zone on convective heat transfer, metal wettability, the surface free energy, friction and wear, cutting forces tool wear and their mechanism were analyzed and researched. The main research work is as follows:Based on general properties of gas discharge, the gas discharge form and the occurrence conditions of ionized air assisted cutting were determined. The evolvement rule of gas discharge with different electrode structure and discharge power was researched. The discharge status with the DC and AC power in air and nitrogen atmosphere were analyzed and the plasma properties were decided. The results show that nitrogen plasma jet (NPJ) and ionized air jet (IAJ) generated by AC pin-cylindrical corona discharge are suitable for the gas discharge form of ionized air assisted cutting. On this basis, ionized air generating device that can produce stable NPJ an IAJ was built.The combination of discharge parameters of ionized jet assisted cutting was optimized. Based on voltage characteristics of gas discharge in atmospheric pressure, the influence law of discharge parameters on the ion concentration of IAJ and ozone concentration was studied. The results show that IAJ with a higher concentration of ions and ozone can be achieved on the condition of being as close as possible to the nozzle, the high discharge power, the nozzle air pressure0.1MPa, the nozzle exit diameter of4mm, the needle tip to the nozzle exit distance0.5mm. Evaluated by plasma jet scales, the influence of discharge parameters on the NPJ occurrence of efficient was researched. The results show that a larger scale NPJ suitable for the ionized jet assisted cutting can be produced with the nitrogen flow rate of1.0m3/h, the needle tip to the nozzle exit distance of2.5mm, the nozzle exit diameter4mm. The function mechanism of ionized jet on cutting zone was revealed. On the analysis of the Rehbinder effect and the principle of plasma solid surface modification, the ability of strengthening tablet on the convective heat was studied respectively using the needle-plate discharge and pin-tube discharge. The results show that both electrostatic ion wind and IAJ can improve the thermal efficiency of the convective. The effects of ionized jet on the wettability of the solid surface were experimental revealed. The results show that free radicals caused by the gas discharge can improve the wettability of the metal and non-metallic surface in a short period of time. The higher the discharge voltage and the longer the processing time, the better the surface hydrophilic. The processing of larger voltage or a longer period of time can achieve super-hydrophilic surface with the contact angle of0°.The lubricating mechanism and cooling effect of ionized air on difficult processing material cutting were studied.selecting TC4titanium alloy,304stainless steel and quenching hard45steel and carbide YG8to constitute friction pairs, friction wear experiments were researched in air, air jet, IAJ, nitrogen Jet, and NPJ atmosphere respectively. SEM and EDS were used on the friction surface morphology and composition analysis. The results reveal the laws and mechanism of action about anti-friction effect of ionized air on difficult-to-cut materials. The results show that NPJ has the best friction and wear properties for TC4titanium alloy due to TiN anti-friction film most easily was formed in the friction surface. For304stainless steel and hardened of GCrl5, IAJ can generate oxide films with good lubricating properties in the friction surface quickly, so it has better lubricating and cooling effect.In order to inspect the lubricating and cooling effect of ionized air to difficult-to-machine materials, the cutting experiments of TC4titanium alloy were conducted in the nitrogen gas jet and NPJ respectively. The cutting property of304stainless steel and hardened GCr15in the nitrogen gas jet and NPJ was experimental proved. The influence of ionized air on cutting force and tool wears in the different cutting speed and cutting depth was studied. The results show that cutting force and tool wears are significantly reduced in the influence of ionized air. It also show that the higher cutting speed, the bigger cutting depth, and more serious temperature and stress state are beneficial to the lubricating and cooling effect and the effect of reduce tool wears.