Two-stage electrostatic precipitators are widely used in oil particle purification in industrial workshops, kitchens and ship cabins. As described in this paper, a two-stage electrostatic module was designed, and the effects of seven parameters on the efficiency of collecting oil mist particles with different particle sizes were studied experimentally. On the basis of these experimental results, a semi-empirical efficiency model was developed, and the measured efficiency and calculated efficiency of the present model and the Deutsch model were compared. The comparison results show that the proposed semi-empirical model can well predict the fractional efficiency of the two-stage ESP, whereas the Deutsch model is clearly not applicable in this case. In addition, the degree of influence of seven parameters on the two-stage ESP collection efficiency was studied by using the single factor sensitivity analysis method with the experimental data. The results show that the degree of influence of various parameters on the particle collection efficiency of 031 pm, from high to low, is as follows: the voltage applied to the precharger, the heteropolar distance of the precharger, velocity, the heteropolar distance of the collector, the voltage applied to the collector, the length of the collector plate, and the length of the precharger grounding plate. (C) 2019 Elsevier B.V. All rights reserved.