The compressed air oil mist filter is composed of coarse filtration and fine filtration, and the air containing high-pressure oil mist first filters the fine metal particles and macromolecular oil particles through the surface filter cotton screen, and then enters the rear high-efficiency ultra-fine plant fiber filter layer, which can completely filter out 95% of the oil mist particles above 0.3um; Finally, the clean air is discharged through a high-efficiency filter. At the same time, the filtered oil droplets through the oil drain port under the filter housing and returns to the machine tool through the oil drain pipe. The clean, filtered air enters the subsequent instruments and gas equipment. For the production equipment of the enterprise, the life and product qualification rate have been greatly improved.