Abstract: Effects of different photoperiod treatments on barley seedings growth were investigated by changing different photoperiods．Growth index and soluble protein content of barley seedlings were measured by using different photoperiods（8, 10, 12, 14, 16 and 18 h/d）after soaking seeds and accelerating germination, and the best photoperiod was obtained．Results showed that photoperiod had a certain effect on growth of barley seedlings．Stem diameter, leaf area and dry weight of barley seedlings treated with 18 h/d light were the largest．Fresh weight and plant height of barley seedlings under 12 h/d light treatment were the highest, and soluble protein content of barley seedlings under 16 h/d light treatment was the highest．In general, 16 h/d light treatment was suitable for large-scale production of barley seedlings in plant factories．