Abstract: According to the data obtained from experiments and investigation, the model and its model base of crop growth and environmental control economy and result in greenhouse were set up. The knowledge database was established by collecting information and experience of expert. Integrating the predicting purpose of model and reasoning purpose of knowledge base system, a decision support system for greenhouse environment control was established as the goal of maximum ratio of output to input. According to the information of climate inside and outside of greenhouse, and the information of crop growth, the system may give the optimized dynamic value of environmental control parameters, such as temperature, light intensity, air humidity, carbon dioxide, according to different climate conditions. Meanwhile, the control scheme is put forward.