Abstract: In order to explore the morphological characteristics of bud differentiation and its relationship with the growth process of flue-cured tobacco, the flower bud differentiation process of 3 varieties of Guiyan no.5, K326, Guiyan no.3 was observed and the relationship with the growth process of tobacco plants was studied. The results showed that for the tested flue-cured tobacco varieties, the flower bud differentiation process can be divided into two stages including flower bud formation and pollen development. Each of the two phases is further divided into four periods, namely, first bract leaf primordium differentiation stage, first inflorescence primordia formation, second female inflorescence primordia formation, stamen differentiation stage, pollen mother cell formation, tetrad formation, single-celled pollen formation, and 2 cells pollen formation. The bud differentiation of flue-cured tobacco began 27-30 days after transplanting and ended 52-57 days after transplanting, lasting 25-27 days. The difference of growth duration from transplanting to budding of different flue-cured tobacco varieties mainly came from vegetative growth stage and flower bud formation stage. The duration of flower bud differentiation was related to the variety characteristics, the duration of Guiyan no.5 and K326 with relatively more leaves (34 pieces) was relatively long, while that of Guiyan no.3 with relatively fewer leaves (32 pieces) was relatively short. Overall, the patterns of flower bud differentiation and morphological characteristics of different flue-cured tobacco varieties were similar, but the processes of flower bud differentiation and tobacco plant growth were slightly different.