Abstract: In order to know the spatial distribution of Alternaria alternata(A. alternata) and the damage it caused to flue-cured tobacco of different varieties, field investigation trials were carried out systematically, and its niche characteristics in Longyan tobacco growing areas were analyzed from the points of host niche and spatial niche. The results showed that the host niche breadth of A. alternata was quite large to the trial tobacco varieties with the incidence and disease index niche breadths of 0.918 7 and 0.931 4, respectively. The varieties in the order of resistance against A. alternata were Minyan 35 > CB-1 > C2 > Honghuadajinyuan, which indicated that the germs basically infected all the trial varieties. Moreover, its spatial niche breadth was also large. The varieties in the order of the spatial niche breadth of A. alternata incidence were Minyan 35 > C2 > Honghuadajinyuan > CB-1, while in the order of the spatial niche breadth of disease index were Minyan 35 > CB-1 > Honghuadajinyuan > C2. It suggested that the germs could fully occupy the upper, middle and lower parts of tobacco plant and cause damage to whole plant. Knowing the distribution of A. alternata and the resistance of different varieties would be helpful to its effective control.