An existing technology for reducing caffeine uses chemical additives such as active carbon, dichloromethane, etc. The present invention provides a method for reducing caffeine through an ecosystem. Accordingly, an ecosystem in a process for reducing water soluble caffeine included in green bean is applied. According to the present invention, water and extra processes are added to the green bean without chemical additives so that water soluble caffeine can be removed up to 50%.COPYRIGHT KIPO 2015에코시스템을 통한 카페인저감