[Objective] The spatio-temporal variation of groundwater in the south rim of Tarim Basin was explored to rationally arrange the monitoring well, and also to realize the rational utilization of water resource and the sustainable development of the oasis. [Methods] Geostatistical method was used to analyze the spatio-temporal variation of groundwater based on the data between 2008 and 2014. Firstly, Gauss model, Spherical and Exponential models were compared to determine which one performed best; Secondly, a chose model was used to analyze the spatio-temporal variation of groundwater in study area, and to optimize monitoring well; At last, Thiessen polygons method was used to calculate the average depth of groundwater and get the variation characteristics of groundwater depth from 2008 to 2014. [Results] Gauss model was the best model in analyzing groundwater change. The spatial heterogeneity and connectivity were enhanced, and the optimization of monitoring wells could be reduced from 23 to 12. The variation of mean groundwater depth was relatively stable. [Conclusion] Groundwater was influenced significantly by the oasis expansion. However, it was still in safe situation counterbalanced by runoff supply. In order to keep oasis development sustainable, it is important to control oasis expanding based on the present oasis scale.