In the current online game field, many studies on the realization of AI have been carried out. It is, however, very hard to apply smart AI to the online games due to the limited use of resources. The Fuzzy extension method this thesis presents is suitable to online games because it causes less loads in the system and makes it possible to realize more human-like AI. To realize this kind of AI, this paper suggests AI system design methods suitable to fuzzy-based online game and presents practical plans to apply them through the produced demos.