Abstract: Uncertainty is normally ignored in land use planning, leading to the over-tight constraints, and the failure of the plan. Although scholars have paid attention to the elastic space of the planning, little has been done to calculate the magnitude of the space. This paper attempts to measure the elastic space of the land use structure using the spatial optimization model based on the consideration of uncertainty, so as to assist the designation of the elastic space of land use planning. The land use structure can be view as the outcome of the social and economic activities that are practiced on the land, thus social and economic activities and land use structure can be taken as the independent variables and dependent variables, respectively. Since the index of social and economic activities is subject to uncertainty, the land use structure is also subject to uncertainty, and this uncertainty can be reflected in the elastic space of land use structure.