Abstract: In order to explore the effects of gibberellin, potassium fertilizer and their interactions on photosynthetic characteristics, chemical components, organic potassium index of flue-cured tobacco leaves, field experiments were conducted in which 10 and 20 mg/kg gibberellins were sprayed on the leaf surface and 75 and 150 kg/ha sulfate potassium fertilizer were applied at the root of the Yunyan 87 flue-cured tobacco on the day of topping. The results showed that: T1-T4 treatments of gibberellin and potassium fertilizer interactions could significantly increase the photochromic pigments and photometric parameters of tobacco leaves. The contents of reducing sugars and total sugars increased significantly, while the contents of nicotine and total nitrogen decreased significantly. The organic potassium index increased by 79.1%-214.0% compared with the control. The total contribution rates of gibberellin, potassium fertilizer and their interactions to photosynthetic characteristics of tobacco leaves were 52.7%, 43.9% and 3.4%, respectively, the rates of chemical composition were 40.1%, 37.2% and 22.7%, and the rates of organic potassium index were 55.2%, 34.2% and 10.6%. Overall, gibberellin was the main influencing factor. Gibberellin and potassium fertilizer had a significant effect on improving photosynthesis, internal quality and organic potassium index, among which the T4 (20 mg/kg GA₃+150 kg/ha K₂SO₄) treatment was better than the other treatments.