Effects of relative soil water content on the content of hormone in pistachio seedling leaves were investigated. The result indicated that the content of ABA and IAA rose and the content of ZA declined with the reduce of the relative soil water content. But there was no difference about the ratio of ABA/IAA when the relative soil water content varied from 80% to 20%.It was the mechanism of drought resistance in pistachio seedling that kept a content ratio of IAA/ABA under drought stress condition.