Three-section type filter

The utility model discloses a three-section type filter. The three-section type filter comprises a bag filter, an HEPA (High Efficiency Particulate Air) filter and an active carbon filter which are sequentially communicated from front to back, wherein an air inlet is formed in the front end of the bag filter; an air outlet is formed in the tail end of the active carbon filter; the air inlet can be connected with a tapered pipeline; and the air outlet can also be connected with the tapered pipeline. The three-section type filter is reasonable and simple in structure, convenient to use, good in air purifying effect and capable of completely clearing away impurities from air, thereby ensuring the stable and controllable reaction process in a low-temperature plasma high-pressure reactor.