Drip irrigation is a kind of modern water-saving technology, moist soil and root zone distribution is consistent.It can use water resources effectively, improve the utilization coefficient of irrigation water.SH dwarf rootstock is bred by Institute of Pomology, Shanxi Academy of Agricultural Sciences, to adapt to China's natural conditions.To determine reasonable drip irrigation upper limit of young SH dwarf apple trees, we conducted an experiment to test the physiological indexes under the condition of different irrigation upper limit in arid and semi-arid area of Jinzhong, Shanxi.With four kinds of irrigation treatment T1, T2, T3 and T4 as test sets and surface irrigation CK as the control, the influence on leaf water potential in the early morning, new shoots growth, trunk diameter and photosynthesis properties was analyzed.It is concluded that the most suitable irrigation upper limit is 90% water-holding capacity when the lower limit is 60% by using principal component analysis.This level is most appropriate to the growth of young SH dwarf apple tree in test area.The results can provide reference and guidance for pilot production.