The invention provides a method and a system for separating and classifying different parts of tobacco leaves. The system comprises a butt putting and leaf laying conveyor, a slitting and separating machine, a stem end tobacco conveyor, a leaf tip tobacco conveyor and a leaf base conveyor. Different parts of the same grade of tobacco can be slit, classified and collected, and then are quantitatively packed, so that when the following tobacco leave-beating and re-drying are carried out, according to chemical compositions of different parts of tobacco, a formula is accurately made, thereby effectively improving the quality of cigarette products. In addition, the leaf laying, butt putting and slitting procedures before tobacco leave-beating and re-drying are adjusted to a sorting workshop, so that the process flow is shortened, materials are quantitatively and accurately prepared, the production environment of a main production line is improved, the breakage rate is effectively reduced, and the production cost is reduced.