The metal working fluids(MWFs) is atomized due to the highspeed rotating of machine tool spindle in the process of machining,and a large amount of oil particles are produced.In order to study the influence of mineral oil characteristics on the emission of oil mist in machining,an environmental chamber experiment method was used to study the emission rate,particle size distribution,median mass diameter and average Sauter diameter of two cutting fluids with different physical properties under different rotation speed.Results show that the total particle emission rate produced by centrifugation shows a quadratic relationship with the rotation speed of spindle.The greater the spindle speed is,the greater the oil mist emission rate of each particle size is,but the spindle speed has little effect on the particle size distribution,the proportion of each particle size,the median mass diameter and the average Sauter diameter.The higher the viscosity of the metal cutting fluid,the larger the oil mist particle emission rate,the median mass diameter and the average Sauter diameter.