Abstract: Assessment and prediction on the regional water environment carrying capacity based on process is of great significance to the social and economic sustainable development. Dongchang lake and its basin was selected as the study area. Vensim software was used to build the water environment dynamics model, which was consisted of social-economic system, water resources system and water environment system. 11 indexes of water environment carrying capacity, including the GDP per capita, rate of urbanization and so on were selected, and fuzzy comprehensive evaluation method was used in the planning year of 2008, 2015, and 2020. And 3 kinds of improved schemes (resource & environment constrained type, social economy constrained type, coordinated development type) together the planed scheme were proposed. Results showed that: pollutants discharges in the planed scheme exceeded the control target, and the concentration of COD, ammonia nitrogen and TN concentration in 2020 were 43.61 mg/L, 2.16 mg/L, and 2.85 mg/L in Dongchang Lake, respectively, with the water environment carrying capacity as the low level of 0.17 in 2020. The coordinated development scheme not only improved the lake quality significantly (in 2020 the concentration of COD_Cr, ammonia nitrogen, TN and in Dongchang lake were 22.56 mg/L, 1.13 mg/L, and 1.41 mg/L, respectively), but also increased the water environment bearing capacity to 0.67, which was higher than other schemes. Under the condition of coordinated development scheme, the average COD_Cr and ammonia nitrogen concentration was expected to meet the lake’s target water quality in 2020. So the coordinated development scheme was selected as suggested scheme, and some suggestions were put forward.