In order to make clear the relationship between physiological fruit drop and 3 kinds of hormones IAA,GA₃ and ABA,we used Xinjiang Zhipi almond to study the dynamic change of three kinds of endogenous hormones in new shoots,fruiting branch sections,young fruits and fruit stalks of the normal fruits and fruits which was about to fall.The fruit setting rate was also tested by applying these three hormones on different tissues,respectively.The results showed that:(1)The changing tendency of three kinds of endogenous hormones in different tissues were consistent with the growing of new shoots and physiological fruit drop.(2)During the physiological fruit drop,GA₃ and IAA in the normal fruits was always greater than that of the fruits which was about to fall.The hormones in the fruit stalks of normal ones were also greater than that in fruit stalks of the dropping ones.Changes of ABA were just the opposite.(3)It was proven by the internal analysis and external applying of these hormones that high level of GA₃ and IAA,and low level of ABA in young fruits and their stalks were helpful to fruit set;Concentration ratio between endogenous hormones in new shoots and young fruits was an important factor for the regulation of physiological fruit drop in almond.High level of GA₃(new shoots )/GA₃(young fruits),IAA(new shoots)/IAA(young fruits) and low level of ABA (new shoots)/ABA(young fruits) would induce fruit drop,vice versa.