Abstract: The method of scenario analysis is introduced into environmental planning. Based on former studies, the main steps suitable for environmental planning are proposed as follows: identifying objects, focal issues and key decisions, listing core elements, ranking driving forces by importance and uncertainty, selecting central scenarios, plotting drivers and scenarios, fleshing out scenarios and putting into practices. Besides, Lake Qionghai Basin, Sichuan Province is further employed as a case study. With system dynamics (SD) model and inexact fuzzy multiobjective programming (IFMOP) model, four scenarios from 2005 to 2015 are properly designed, scientifically quantified and finally analyzed. Results indicate that the basin is facing more and more pollutions; however the related investment is rather a big burden for the local economy. Apparently, seeking new investments is urgent for the environmental improvement in Lake Qionghai Basin.