Abstract: To explore the impact of UV-B irradiation on Arabidopsis seed germination and seedling growth, we treated seeds of Columbia wild-type Arabidopsis with artificial UV-B and examined germination potential, germination percentage, root length, plant height, and contents of chlorophyll, soluble sugar, soluble proteins and malonaldehyde (MDA). A short period of UV-B irradiation promoted Arabidopsis growth, with a significant effect at 1.0 kJ·m^–2 (P<0.05), with peak germination potential and percentage, as well as root length, plant height, and contents of chlorophyll, soluble sugar and soluble proteins. However, MDA content was not affected (P>0.05). With doses > 1.0 kJ·m^–2, the promotion was reduced and was inhibited with longer irradiation. Thus, suitable UV-B irradiation dose could promote seed germination and seedling growth of Arabidopsis, and a too-high dose is an inhibitor, inducing damage.