Abstract: The effects of different molybdenum ion levels on growth, photosynthetic characteristics, antioxidant enzyme activity and chemical properties of tobacco plants were investigated by nutritional liquid hydroponic and potted experiments. The results showed that when the molybdenum ion concentration was 0.04 mmol/L, during the seedling period of tobacco, the treatment can effectively improve the absorption of nitrogen, phosphorus and potassium, promote the growth of the seedlings, and improve the quality of the seedlings. During the field period of tobacco leaves, when the added Mo ion concentration was 0.30 g/plant, the MDA and OFR contents of tobacco plants were the lowest, which could alleviate the damage of active oxides to cell tissues and improve the tolerance of tobacco plants. At the time, the chemical components of tobacco leaves had good coordination.