Abstract: Multi-agents model (MAS) is an effective tool for studying and simulating complex social and economic systems. MAS model itself does not have complicated modeling steps, but gives a modeling ideas and mechanisms of "from micro to macro and from bottom to up". In China, market mechanism and planning mechanisms are the major driving and regulation forces of urban residential space evolution. This paper builds an urban residential space expansion model based on GIS and MAS that contains micro intelligent agents and environment agent, aiming to investigate the interactions between the market mechanism and planning mechanism in the process of urban residential space transformation. On the basis of the cognition of the behavior characteristics of the market mechanism agents of urban residents and property developers, the model analyzes the impact of the two market mechanism agents on the evolution direction of urban residential space, and the paper points out that under the policies of state-owned urban land in China, the urban government's land supply decides the urban residential evolution patterns and the total benefits of residential land development. Thus, by adjusting the land use and environment protection policies of urban government, the model sets three policy scenarioes and achieves the preview of the evolution of residential space for each scenario, which can provide guidance for land use planning in advance. Wuchang and Hongshan districts in Wuhan city are chosen as the experimental areas. By the MAS model the paper compares the land use structure and land use benefits in the process of the residential space evolution from 1998 to 2008 among the three scenarioes and the actual situation respectively. Some main conclusions can be drawn as follows from the model’s outputs. Firstly, there are always intersections between the real residential space evolution and the model’s simulated results under different scenarioes, which means that because of the influence of macroscopic environment, urban government may adjust its land use policy, natural environment protection policy and so on in different periods. this is just one of the characteristics of Chinese real estate market. Secondly, urban residents’residential favor can affect the spatial form and the speed of urban residential space’s growth. The third is that compared with land redevelopment of the old urban area, newly developed land in inner suburban districts has a lager proportion in the evolution process of the residential space from 1998 to 2008 in the two experimental districts. In fact, the government of Wuhan city had focused on the development of new residential land in the suburban fringe areas before 2004, but the emphasis has been transferred to the old city transformation and land redevelopment after 2004.

Key words: GIS, land use, multi-agents, scenario analysis, urban residential space evolution, Wuhan