The appearance quality determination of tobacco leaves is currently highly dependent on human judgment, and looking for objective methods is of increasing concern. The microstructure of tobacco leaves is the basis for appearance quality, thus the studies of microstructure of tobacco leaves could provide a reference for quantitative methods of appearance quality analysis. In this study, some flue-cured leaves of the same grade (C3F) were collected in China. The cell area, cell porosity and unit cell porosity of these samples was analysed by SEM imagery and quantitative analysis by Photoshop. The results were as follows: 1) The cell structure index of flue-cured tobacco leaves from different planting areas was obviously different from each other, the range of cell area was 3500 µm² ~ 6400 µm², and the cell porosity was 9.8%~14.7%, and the unit cell porosity was 12.5%~25.0%; 2) The cell structure showed regular regional distribution to a certain extent: Cell area of leaves from southeast planting area was significantly larger and the porosity was relatively small; Cell area of leaves from north planting area was obviously smaller and the cell was folded significantly; Cell shape of leaves from Huanghuai planting area was mainly flat, the cell was folded relatively small and cell size distributed inconsistently; Cell size of leaves from southwest planting area was comparatively uniform and the porosity was relatively large; 3) Unit cell porosity could be used as the index to evaluate the loose degree of organisational structure of flue-cured tobacco leaves.