Air cooling is a near dry machining method, which cools cutting area and evacuates chip using low temperature wind instead of cutting liquid. It can decrease tool wear, improve tool life, reduce cost and produce no chemical pollution. In this paper, air cooling system is established, in which vortex tube is used for cooling. Air cooling test was carried on, in which high hardness bear steel GCr15 is machined by PCBN tool. Experiment results indicated that cold air from vortex tube has a significant effect on cutting force, cutting temperature and chip formation process. Cutting force and cutting temperature were simulated using Marc. Change rules that analysis results indicated are in accordance with experiment results. This paper’s conclusions have a great reference value for the practical application of air cooling technology.