Abstract: Abstract: Ultraviolet radiation (UV-B) radiation is a key environmental signal for plant growth and development. An excess or lack of UV-B can affect plant resistance, yield and quality. However, the appropriate dose of UV-B for cucumber seedlings growth in plant factories is not well understood. In this study, the effect of different doses of UV-B radiation on the growth, physiology and antioxidant systems of cucumber seedlings in an artificial climate chamber was studied. The results showed that UV-B radiation effectively inhibited the elongation of cucumber seedlings by 4.2%-32.0% and decreased soluble protein content in cucumber leaves by 14.2%-28.2%. 3.33 μmol/(m2·s) UV-B promoted stem diameter growth, soluble sugar content, total ascorbic acid and the superoxide dismutase, peroxidase and catalase activities in cucumber leaves by 13.6%-22.3%, 22.7%-56.7%, 16.9%-23.2%, 23.8%-25.9%, 34.1%-50.4% and 27.4%-36.4%, respectively. However, this UV-B dose had no influence on the net photosynthetic rate of cucumber leaves. Therefore, we conclude that 3.33μmol/(m2·s) UV-B is beneficial for growth and increases the resistance of cucumber seedlings in an artificial climate chamber. This study is hoped to provides a theoretical basis for cucumber and other seedling growth under UV-B treatments.