The operation process of metalworking lubricants affects the formation of oil mist, including mechanical equipment, physical and physical chemical forms. In order to effectively lubricate, cool and clean, metalworking lubricants should be subjected to pump circulation, spray, jet and high-speed cutting tools, and high temperature evaporation. The form of oil mist is different, and the particle diameter area is also quite different. Generally, the oil mist produced in the atomization process of mechanical equipment is mainly in the form of droplets, and the droplet diameter area is wide, generally 2 ~ 10um. During the condensation process, the oil vapor produced by evaporation will also produce extremely fine condensed suspension with particle size less than 2um. The results show that the larger distribution area of oil mist particle size in the air of the workshop is 1 um. The test results of oil mist particle size around the CNC grinding machine show that 95% of the droplets are less than 3 um. The total hydrocarbon content in the air of the processing workshop is much higher than that of the oil mist test value due to the large amount of evaporation of lubricants. However, medical research has proved that the harm of oil vapor and large particle droplets to human lungs is relatively small. The oil mist in the state of oil vapor is inhaled into the lungs and exhaled. These are not captured by the alveoli, and the large oil droplets cannot enter the lungs through the nose and bronchus. The oil mist particles can only be stored in the form of droplets and can reach the alveoli successfully and precipitate in the lungs, thus causing harm to the human body.