Abstract: Abstract: Fluorescent in situ hybridization (FISH) technique, 45S rDNA as probe, was established in narcissus in the study. It showed that the modified procedures could be further used to identify genetic relationship narcissus cultivars. Flame-drying protocol after enzyme digestion of cell wall was a good method for getting clear and well dispersed narcissus chromosome. With probe DNA labeled by nick translation, and co-denaturation of chromosome DNA and probe for 5 min at 90℃, the rDNA was successfully localizated by FISH method.