This article studies the soil moisture conditions of 30 years artificial Robinia pseudoacacia in the north of Shaanxi under different climate conditions in order to explore the relationship between soil moisture and impact factor of Robinia pseudoacacia in this area, and variation characteristics of soil moisture in the Loess Plateau region. The results show that soil moisture content decreases with increase of soil depth, and in 40-50 cm depth the jump point of moisture reduction appears significantly. Soil moisture was lower than the growth critical moisture in 5 samples to the north of Chunhua, and has different degrees of deficit. Soil moisture deficit degree was more than 50% in sandy loam and light loam soils such as Yulin, Shenmu and Suide. With the increasing of latitude, both of soil accumulative storage and net rainfall tends to decrease, but the relationship between them is significant correlation, indicating that that climate conditions are the major factors causing significant difference of soil moisture.