Abstract: The water resources in Mongolia are a vital and sensitive to change of the weather. The results if the climate changes show as the form of ruining of water resources, the lakes and ponds become surprisingly dry. All the surface water runs down to ground water levels, at the summer seasons there is always an extreme heat, as the result of this heat, there is always severe desertification because of the lack of rain precipitation and eventually the drought is eminent, consequences are that of soil change of its characteristics, withering of some species of plants, deterioration of the environment and subsequently the ecosystem in Mongolia. Its truth and fact that water are the vital resources of all the natural resources of which all the living thins depending on, be it surface water, hydrological, streams, the change in the hydrological system in the ecosystem is the change of most of living thing that needs water. The fluctuation of the climate is not only changing the hydrological system, but it also inflicts a serious changes of economic circular, and this change in economic or climate also change the demographic distribution of mankind. Therefore, the expected future change in Mongolia will also affect sustainable environment in the region and Mongolia in