Filtering device with third stage and fourth stage

The utility model discloses a filtering device with a third stage and a fourth stage, which comprises a barrel body provided with at least one containing space with an opening, a first end of the barrel body is provided with an air inlet, and a second end of the barrel body is provided with an air outlet; the barrel cover is used for covering the opening; air to be filtered enters the third-stage filtering piece from the air inlet to be subjected to third-stage filtering; the air filtered by the third-stage filtering piece enters the fourth-stage filtering piece for fourth-stage filtering, and then is discharged from the air outlet; wherein a gap is formed between the filtering layer of the third-stage filtering piece and the inner wall of the barrel body to form a first air channel, and a gap is formed between the filtering layer of the fourth-stage filtering piece and the filtering layer of the third-stage filtering piece to form a second air channel. Therefore, the yield of customers is improved, and the p