The utility model discloses a quick fastening structure of an air filter. Relating to the technical field of gasoline engines, the quick fastening structure of the air filter comprises a fastening buckle, an outer cover of the air filter and an inner cover of the air filter, wherein the fastening buckle is provided with a T-shaped clamping structure; the air filter inner cover is provided with a guide groove and a semicircular clamping groove structure, the air filter outer cover is provided with an installation hole, after the fastening buckle penetrates through the installation hole of the air filter outer cover and the guide groove of the air filter inner cover, the T-shaped clamping structure of the fastening buckle can be screwed into the semicircular clamping groove structure to be clamped, the purpose of locking can be easily achieved, and the fastening efficiency of the air filter is greatly improved.