The invention belongs to the technical field of lawn-mower accessory applications, and particularly discloses a wear-resistant positioning shell structure used in a carburetor of a lawn mower. The structure includes a foursquare positioning shell body, first positioning holes, a round limit bump and a strengthening-rib ring, wherein the first positioning holes are arranged at the interiors of four corners of the positioning shell, the round limit bump is arranged on the foursquare positioning shell body, the strengthening-rib ring is arranged in the round limit bump and used in coordination with the foursquare positioning shell body, and the strengthening-rib ring is fixedly connected with the foursquare positioning shell body by a bolt. The structure has the advantages that the integrally-formed structure is reasonable in design and is used in coordination with the strengthening-rib ring, auxiliary heat dissipation holes and the like, and the structure is long in service life and high in service efficiency and does not need to overhaul frequently; a first positioning lug and a second positioning lug solve the problems that current lawn-mower positioning shells are inconvenient to install and maintain and easy to loose, and the positioning of the current lawn-mower positioning shells is unstable and inaccurate. Meanwhile, the structure is wide in application range, safe and reliable to assemble and use, and convenient to clean and maintain, and the assembly efficiency and the overhaul efficiency are improved.