How to assess environmental impact is one of the keys in land use planning. This article described in detail the concepts of activities, impact zones, functions, and sensitivities, as well as the development of STEPP (strategic tool for integrating environmental aspects in planning procedures) based on Avenue, the secondary developing language of ArcView GIS. The system makes it convenient for planning practitioners exchanging information, and can spatially, visually and quantitatively describe environmental impact and its change. In this study, the urban-rural combination area located between EDE and Veenendaal of The Netherlands was taken as case, and the results indicated that the environment was incorporated well in the planning procedure based on the concepts, and could also demonstrate the effects of planning measures on environment spatially, explicitly, and in real-time, facilitating the participation of planning practitioners and decision-making. Some proposals of how to promote STEEP application in China were suggested.