Abstract: The genetic characteristics of potassium content in leaves of FCV parents SC58, Zhongyan14 and their F₁, F₂, F₃ families were analyzed with major gene-polygene mixed inheritance theory.Two methods were used to analyze heredity of potassium content in leaves.The first one was F₂ generation graphical analytic method, the results demonstrated preliminarily the presence of major gene in the heredity of potassium content in leaves.The second method was P₁, P₂, F₁, F₂, F₃ families multi-generation joint analysis, the result indicated that the inheritance of potassium content conformed to model D (major gene + polygene).The results from these two analyses suggested that the best model of potassium content inheritance in flue-cured tobacco was major gene + polygene, the mixed inheritance model.From the analysis of inheritance effect, it is considered that the inheritance of potassium content in flue-cured tobacco leaf was mainly negative dominant effect (h=-0.612), additive effect was insignificant (d=-0.05).The total heritability was 55.55%, the major gene heritability was 52.78% and polygene heritability was 2.78%.