Abstract: To investigate the seed dormancy and seed germination characteristics of Iris plants, the seeds from 20 species of Iris plants were used as experimental materials to study time progression of seed germination, germination rate and corrected germination rate index under Eight temperature treatments（30 ℃, 25 ℃, 20 ℃, 15 ℃, 30 ℃/20 ℃, 25 ℃/15 ℃, 20 ℃/10 ℃, 15 ℃/8 ℃） were studied in two groups(cold stratification for 0 d and 60 d respectively. The results showed that seed dormancy and germination characteristics of Iris plants were significantly different among species. Among the 20 species tested, the seed germination rate of 9 species was greater than 80% within 30 days, and the seeds were not dormancy. Also, the seed germination rate of 11 species was less than 80% within 30 days, and the seed dormancy was different in type and depth. The physiological dormancy was observed in Iris setosa, Iris chrysographes, Iris bulleyana and Iris laevigata. Warm stratification could break the dormancy of Iris kobayashii and Iris ventricosa, while cold stratification for 60 days could break the dormancy of I. setosa, I. bulleyana, I. chrysographes and I. laevigata. Cold stratification for 60 days could increase the seed germination rate of most non-dormant Iris plants, but decrease the seed germination rate of Iris species. Among the 16 non-dormancy and medium-light dormancy species of Iris, 5 species were not suitable for cold stratification for 60 d, and the optimal germination temperatures were 25 ℃, 20 ℃ or 25 ℃/15 ℃, respectively, and 11 species