Abstract The objective of this paper is to develop a knowledge-based computer system for zoning in land use planning. It discusses how to acquire knowledge from experts and how to utilize this information efficiently. IF-THEN production rules can be derived from the “knowledge structure digraph map,” which is obtained by structuring the conscious expertise of planning professionals. A new model concerning the combination of these rules, based on fuzzy inference, is developed in order to simulate human inference more appropriately. A practical application of the system is given and its applicability is discussed.