The utility model discloses a multistage filtering oil bath type air filter. The device comprises an outer shell and a fine filtration assembly, the outer shell is sequentially composed of an upper cover body (3), a middle shell body (7) and a lower shell body (16), an air inlet pipe (6) is installed in the middle shell body, a primary coarse filtration assembly (5) is installed at the upper end of the air inlet pipe, and a dust accumulation cup (4) is installed between the upper cover body and the middle shell body and on the side of the primary coarse filtration assembly; wherein the fine filtration assembly is arranged in the middle shell and the lower shell and is sleeved with the lower end of the air inlet pipe, a secondary fine filtration assembly (17) is arranged in the lower shelland below the fine filtration assembly, and the middle shell is externally connected with an air outlet pipe (22). Air is sequentially filtered by the primary rough filtration assembly, the secondaryfine filtration assembly, the fine filtration assembly, the foam sponge and the like for multiple times, the multi-stage design is scientific and reasonable, the structure is compact, the cost is saved, the filtration effect is obvious, clean air is provided, and the overall quality of the filter is remarkably improved.