The processes through which structure of ecosystems ends to its functions, according to the principles of environmental planning are called development. Since our environment consists of numerous ecosystems, and the complexity of action and reactions of developments emanates in cybernetic ecosystems, we need to use models, in order to predict and grasp a meaningfull perception of the real world. But in some instances modelling and the use of models become too complicated, which potentially increase the uncertainty in predictions. This paper, is an attempt to elucidate these kinds of model like MLR, and AHP and to present some solutions like uses of Game Theory in spatial planning, reduced models in simplification of models, and matrix quantification of SWOT model. Finally, it is argued that model should act as a decision support system (DSS) in environmental planning.