Taking the Dunhuang oasis as a case study, this research aims to fully analyze the evolution of oasis agricultural water use, ecological water use and social economy water use, on this basis, we select many suitable water resources security evaluation index to establish evaluation system, and under the background of current region water resources planning, we apply the system model to predict the future evolution of oasis water structure under different scenarios. The basic conclusion and understandings as follows：（1）during the 1987-2007 The expansion of the artificial oasis reduction in natural vegetation area.（2）the estimated total water consumption of the study area increased from 4.00×108m3 in 1987 to 4.75×108m3 in 2007, representing an average annual increase of 3.6%. Agricultural water consumption has been the largest of all classes during the period from 1987-2007. （3）the water resources security of Dunhuang oasis under an unstable condition. The response indicators show that the local water management measures should be strengthened, especially in fundamentally solving the problem of groundwater exploitation excessive in irrigation area.