Abstract: To explore the effect of citrate-soluble silicon fertilizer on physiological indexes and quality of flue-cured tobacco, a field experiment was conducted to study the effect of different gradient of a citric acid-soluble silicon fertilizer on antioxidant enzymes, pigments, and conventional chemical composition of flue-cured tobacco. The results showed that:(1) The silicon fertilizer significantly promoted SOD and POD activities and reduced MDA content in flue-cured tobacco. (2) The silicon fertilizer had an effect of first decreasing then increasing of chlorophyll content. Chlorophyll content gradually increased 45 days and reached the maximum value on the 60th day after transplanting. The treatment applying the silicon fertilizer of 50 kg/667m² significantly increased chlorophyll content and carotenoid content, which could be the physiological basis of improving the quality and yield of flue-cured tobacco. (3) The silicon fertilizer increased the content of total sugar, reducing sugar and potassium and decreased the content of total nitrogen, protein and chlorine in flue-cured tobacco, all in favor of improving the quality of flue-cured tobacco. In conclusion, the comprehensive effect of the treatment applying the silicon fertilizer of 50 kg/667m² was better.