According to the groundwater balance theory,the groundwater isostatic essence under the conditions of natural and current mining for confined aquifer II in the west region of Xishan has been analyzed.It is shown that about 75%to80%exploited water comes from pressed and released groundwater in clay band.This paper suggests the relationship between groundwater mining and land subsidence.Simultaneously,by the generate mechanism of land subsidence,it analyzes the existent problems of groundwater resources computing model ignoring the influent factor of land subsidence in serious region of land subsidence.To solve these problems,the reasonable computing methods about groundwater exploitable resources is put forward,and the practicable computing model including the influent factor of land subsidence is analyzed.