The utility model provides a cylinder sleeve of an improved structure, and belongs to the technical field of machinery. The cylinder sleeve solves the problem that aluminum sheets are generated in casting of an existing cylinder sleeve. The cylinder sleeve of the improved structure comprises a hollow cylinder sleeve body with a round through hole, and is characterized in that the inner wall face of the cylinder sleeve body is a conical face, and reinforcing ribs are arranged on the surface of the outer wall of the cylinder sleeve body. The inner wall face of the cylinder sleeve body is the conical face, so that no gaps are formed between the cylinder sleeve body and a mounting column, and aluminum sheets can not be produced in the casting process. The cylinder sleeve is simple in structure and convenient to cast, and the blank quality of workpieces can be effectively improved.