Abstract: For reducing the dust concentration in air and the maintenance work for air conditioning system in cigarette manufacturing department, an energy saving and self-cleaning air filtering system was designed on the basis of the distribution pattern of dust particle diameter, which was mainly composed of filter units, cleaning devices and a PLC control cabinet. The filter unit was of modular structure with stainless steel fiber felt as filter material and installed on a rectangular bracket of vertical slot type to increase filtering area. Online automatic cleaning mechanism used the tap water from the air conditioning room, and the both sides of filter unit were cleaned by the high-pressure water stream injected from nozzles. The test results showed that the system possessed a high dust holding capacity, filtration efficiency was higher than 70% with the initial filtering resistance between 32 and 166 Pa. Online automatic cleaning function was realized, the energy consumption of running was reduced, while air filtration efficiency was increased effectively.