Abstract: In order to study the relationship between potassium application rate in different ecological regions and growth and potassium use efficiency of flue-cured tobacco, field experiments were conducted in Jimo county of Shandong province and Luoping county of Yunnan province, which have different climate and soil conditions, the treatments designed included no potassium fertilizer applied (CK) and three application levels of potassium fertilizer (T1 123.75 kg/ha, T2 247.50 kg/ha, T3 371.25 kg/ha for Jimo; T1 67.50 kg/ha, T2 135.00 kg/ha, T3 202.50 kg/ha for Luoping). The results showed that (1) Potassium application caused significant increase in biomass of stems and leaves as well as total biomass of tobacco plants in Jimo, while only significant increase of leaf biomass was observed in Luoping. T1, T2 and T3 treatments caused significant increase of tobacco leaf biomass by 7.62%, 29.4% and 31.5% in Jimo and 12.4%, 19.5% and 13.1% in Luopin, respectively. (2) Potassium application significantly enhanced potassium accumulation in tobacco leaves and total potassium accumulation in tobacco plant in Jimo, with T3 having the most significant effect. Potassium application significantly enhanced total potassium accumulation in tobacco plants in Luoping, with T2 having the most significant effect. (3) In Jimo extremely significant positive correlations were observed between potassium application and yield of tobacco leaves, between potassium content in tobacco leaves and total potassium accumulation. In Luoping these relationships can be represented by quadratic equation curves. In Luoping potassium application rate, yield of tobacco leaves, potassium content of tobacco leaves and total potassium accumulation in tobacco plant of T2 treatment were close to the maximum (6579 kg/ha, 2.19%, 230 kg/ha). (4) For T2 in Jimo, tobacco leaves potassium content >3%, apparent utilization rate of potassium fertilizer (RE) and potassium agronomic efficiency (AE) were up to 27.8% and 2.50 kg/kg, potassium partial productivity (PEP) decreased, soil potassium surplus was significant. For T2 in Luoping, RE was as high as 45.3%, AE (8.05 kg/kg) and PEP (49.3 kg/kg) were higher, soil potassium deficiency was significant. In summary, the potassium application rate of T2 level had a significant effect in improving yield and quality of tobacco leaves, balancing soil potassium and improving the utilization rate of potassium fertilizer, and can be recommended as an appropriate potassium application rate for flue-cured tobacco production in the two regions.