Comprehensively sorting out, sifting and analyzing multi-year monthly data of hydrographical, meteorological, water andland uses, social economy, remote sensing from Yanji Basin, this paper simulated and analysed conditions of water-salt balance ofLake Bosten from 1960 to 2003 using Water-Salt Balance Model. Based on these studies, two projects were provided for developmentplanning of Yanji Basin in the near future. And then, it forecasted and analysed water environments of Lake Bosten in future 40 years.According to the simulation results, some conclusion was following: Though there was exporting salt in an accumulation of average306000t/a that made desalination in the lake, it might increase freshwater and decrease input-salt to reduce the degree ofmineralization of Lake Bosten. After the construction projects in recent years were implemented in Yanji Basin, the degree ofmineralization of Dahu would be limited between 0.84g/L and 1.38g/L according to scenarios of Project B. Under such circumstances,the degree of mineralization of Dahu could be adjusted and controlled under 1.00g/L. The degree of mineralization of Dahu coulddecrease to 1.00g/L in 2040 according to the simulation. Water quality of Kongque River was difficult to restore to original state, butits degree of mineralization could be controlled under 0.60g/L because of the improved water environments of Lake Bosten. Forecastanalysis of Project B showed that it was beneficial to water environments of Lake Bosten when the construction project in the nearfuture was completed in Yanji Basin. And water environments of Lake Bosten would tend to a well-ordered circle.