Abstract: It is very important for the high efficiency mode of apple production to properly select and combine scion and rootstocks. The easy formability and precocious flower of the young trees are the important indexes to screen the excellent combination of the rootstock，which is closely related to the endogenous hormone content. Three- or four-year young trees from five different scion-rootstock combinations of Fuji apples were used as materials to research the relationship among endogenous hormones，precocious flower and easy formability. The results showed that：vigour rootstock apple tree was tall and vigorous，and the proportion of spurs and the number of inflorescence were significantly smaller than those of the dwarf rootstocks. In addition，the proportion of spurs was high，but the amount of flower was little for M26 combination. The tree of M26 was weak，SH16 combination followed，and T337 finally. It showed that the combination of T337 possessed good growth power and more flower. The content of IAA and ZR in young leaves reached the peak when the spring，autumn shoots began to grow. Furthermore，the content of IAA，ZR，and GA3 in the fine root reached the peak when the root was in the second high growth period. There was a negative correlation between IAA in the fine root and ZR in young leaves，and there was a positive correlation between the above-ground and the underground of IAA and GA3. In the critical period of bud physiological differentiation，IAA and ZR in young leaves were positively correlated with the amount of shoots，ZR and ZR/GA3 were positively correlated with the proportion of spurs，and GA3 was negatively correlated with the number of inflorescence. At the second growth peak of root system，the related indexes of flowering were positively correlated with IAA，ZR，GA3 and IAA/ZR in the fine root. It is suggested that endogenous hormones play an important role in flowering and root growth. Therefore，T337 as a rootstock，reflects the integrity of easy formability and early flower.

Key words: apple, young tree, scion-rootstock combination, endogenous hormone, precocious flowering, easy formability