distribution center generally tends to fall into operational disorder due to fluctuation in the quantity and variety of the daily orders. Hence, a novel methodology to deal with such problems is strongly required. This paper presents a new concept called "design space" in order to model the individual operation know-how. The planning procedure for a comprehensive operation can be represented as a chain of small design spaces. We focused primarily on the operation of an order picking system with a conveyor and a pick-to-light in the center. We then performed a problem analysis in order to formulate the practical models of the operation management plans by using design space, and we implemented them as a knowledge base. We carried out a simulation of the future operation plan using the data of a past work log from an actual distribution center and obtained successful results with improved throughput and shorter process time.