Abstract: Maleic hydrazide(MH) was sprayed on a normal longan cultivar (Dimorcarpus longana Lour. cv. Wulongling) to induce the formation of shriveled seeds in longan. The results showed that the contents of gibberellin (GA3),indole-3-acetic acid (IAA) and abscissic acid (ABA) in the shriveled seeds decreased most of the time during fruit development,and the GA3 content reached the minimum at maturation. There was a significant reverse correlation between the formation of the shriveled seeds and the fruit's endogenous hormone content. During seed development,the ratios of ABA/GA3 and ABA/IAA in the seedless fruits were remarkably higher than the control. It was,therefore,concluded that the main reason of the normal longan seeds to become shriveled was due to a reduction of these endogenous hormones.