Abstract: To reveal the physiological mechanism that plant hormones regulates the germination and growth of axillary bud of tobacco, cv. K326 (the variety with axillary buds of strong growth vigor) and cv. Yunyan 87 (the variety with axillary buds of weak growth vigor) were taken as experimental materials. The lengths of the first and third axillary buds (counting from top to bottom of plant) were measured and the changes of IAA, ABA and GA₃ contents in the axillary buds during topping and on the 5th, 10th, 15th, 20th, and 25th days after topping were analyzed. The results showed that the apex shoot of tobacco plants heavily affected the germination and growth of axillary buds, topping could promote the germination and growth of axillary buds. The germination ability and growth vigor of axillary buds increased with the ascent of stalk position. After topping, upper axillary buds germinated earlier than lower axillary buds, and the axillary buds of cv. K326 were longer than those of cv. Yunyan 87 at all stages. The contents of IAA, GA₃ and ABA in axillary buds after topping were significantly lower than those during topping, generally, they decreased first and then increased. After topping, the apical dominance of tobacco plant was removed and the contents of IAA and GA₃ at axillary bud site reduced rapidly, which promoted the germination and growth of axillary buds.