Abstract: Some aspects on the initial fruit set in Younai (Prunus salicina Lindl var. cordata J Y Zhang et al) were studied. The results showed that, large amount of flower/fruitlet drop occurred within 2 weeks after full blossom; low content of GA1+3 was closely correlated to the peak of fruit drop, however, the contents of endogenous zeatin ribosides (ZRs), dihydrozeatin ribosides ([diH]ZRs) and abscisic acid (ABA) were significantly positive correlated to the growth of fruitlet (ovary); during the initial fruit set of Younai, quite a few of female gametophytes degenerated or aborted, and, the developmental process was slow after anthesis, which therefore, blocked fertilization and resulted in flower/fruitlet abscission. The mechanism of initial fruit set in Younai was discussed in this paper.