Abstract: In view of the problem that the conventional vacuum pump air filter is non-self-cleaning and needs to be stopped when replacing the filter element, a self-cleaning combined vacuum pump pre-filter is designed that can replace the filter element without stopping the machine. In this paper, the optimization experiments were performed on the filter air velocity, filter element's structure, and filtration resistance. The experimental results show that the filtration efficiency of the self-cleaning combined vacuum pump pre-filter, when the air velocity is no more than 2 m/min, can reach more than 96.6% for the air with the dust concentration of 15-30 g/m³, but only 90.2% for the air with the dust concentration of 5 g/m³. Considering the two factors of filtration resistance and filtration area, the optimum filtration efficiency was measured when the pleat breadth(b) was 35 mm and the pleat edge angle(a) was 11.7°. In the ratio P/H range of 0-0.2(the ratio of the spacing between adjacent pleated peaks to the vertical height), the filtration resistance decreases rapidly as the ratio increases. After the ratio is greater than 0.2,the reduction of filtration resistance tends to slow down. For the design of the self-cleaning combined vacuum pump pre-filter, the optimal value of P/H is determined based on the consideration of installation space, ash cleaning effect, and resistance.