Dust collecting performance of axial-vane type cyclone for oil mist was analyzed in this study. For predicting cut diameter size of cyclone, the number and angle of vane (${eta}_2{^{prime}}$) was calculated by CFD. As the result, ${eta}_2{^{prime}}$ was decreased as the number of vane was increased and the angle of inclination (${eta}_2{^{prime}}$) decreased, and it cause strong swirl flow. Therefore, it could be confirmed that as the number of vane was increased and the angle of inclination was decreased, cut diameter size was decreased. Also, by verifying the results of CFD through experiment, the cut diameter size could be 2 ${mu}m$ at 4 $m^3/min$ of flow rate.