Based on the analysis of remote sensing images (landsat TM and MSS) of Wuxi in recent 30 years, we found that the landscape of urban-rural transition region was in the form of suburban agriculture before market economy took the dominant position (the mid-1990s of China). After that, the landscape of suburban agriculture disappeared. The urban-rural transition region transmuted from suburban, a concept of administrative division, to urban-rural coupling region with new urban-rural relationship. On the other hand, administrative division adjustment lagged behind the transmutation of landscape and social attributes. In this paper, urban built-up area is composed of consecutive city buildings, and urban-rural transition region is the external region of urban built-up area. Urban and rural areas are the complex giant systems that contain many social, cultural, economic, and landscape factors. And the urban-rural integration results in urban-rural coupling region. The term of transmutation represents not only the evolution of things but also the complete change of the essence of things. Transmutation of urban-rural transition region refers to the complete change from quantitative to qualitative of its space and attribute.
Through the establishment of the transmutation model, urban and rural factors in the transmutation of transition region are divided into internal factors (u) and external factors (v) as control variables. According to analysis of the factors influencing the urban-rural transition region, we found that the external control factors, such as the percentage of built-up area and the index of transportation accessibility, are dominant in transmutation. At the same time, external control factors bring about the changes of internal control factors such as non-agricultural employment population, non-agricultural industries, and construction land. The irreversible changes of the factors, such as expansion of built-up area, lead to an irreversible transmutation of urban-rural transition region. So the transmutation is different from normal catastrophe theory model in irreversibility.
Based on the above-mentioned studies, we provide a scientific basis for overall planning of urban and rural region. By accelerating the changes of external conditions of rural region, we can promote the rural development, and also provide a basis for adjustment of administrative divisions of the city to meet the need of economic development. As a result of the rapid expansion of urban built-up area, urban-rural transition region has almost expanded into the entire administrative area. So the further expansion of urban built-up area is bound to create a form of urban and rural interaction beyond the administrative boundaries.