Abstract: The west of Jilin Province is located in semi-moist and semi-arid climate region and the shortage of water resource has seriously limited the economic development and ecological environment rehabilitation. The concept of ecological environment water requirement of vegetations was put forward, which is the least water requirement to ensure healthy growth and to control sandification, alkalization and even desertification of soil. The areas of farmland, woodland and meadow were calculated based upon RS and statistic yearbooks. The ecological environment water requirement of different kinds of vegetations was calculated by area ration method, water balance method and potential evapotranspiration (ETO) method, and the requirement of farmland, woodland and meadow is respectively (6.0698 billion,) (4.2942 billion) and (3.2852) billion m³. Study on water balance shows that the water requirement is (13.6492) billion m³ and the shortage is (1.925) billion m³ in the area.