Green-space are undeniable necessity in the urban echosystems. Isfahan , regarding this fact that it has become the pivat of industrial development, has been faced with some risks such as: increased population, the conversion of the valuable lands to the constructions and buildings, progressive immigration from other areas, decreased quality and quantity of water and soil resources and increased bio-environmental pollution. If these irregular trends continue to occure, it will jeopardise the continuation of civil life in the city. This research tries to clarifying the importance and the real place of green-space in the process of continuous developement of the urban areas by using a systemic logic and introduces a methocl by which it could diagnose the effective factors related to par-capita green space. A method was purposed to determine the per capita greenbelt of Isfahan city as a model which was included effective parameters such as the needed areas for a tree to grow, the temperature, pollution, and density of people in each room. At the next phase, by separating 12 districts of Isfahan city and combining the relative population method, relative demand method, and relative land method, it was determined the changes in capitation for each district, then evaluated against the other districts. Also, the dynamic systems method was used to analyze the trend of changes from 2004 to 2025. The results from analyzing the data showed that the desired capitation for green-space in Isfahan is 56 m 2 per person. But, considering the desired capitation (56 m 2 per person) in 12 districts, their capitations would change and most of them wouldn’t have the desired capitation (56 m 2 per person) due to low areas in relation to population ratio. Meanwhile, the district 9 has the relative needed capitation. But, higer land in relation to population ratio of the district 12 is higher than desire (56 m 2 per person) due to higher land in relation to population ratio. The prediction of changes in green-space in Isfahan, based on system dynamics showed that the differences between desired green-space and the present situation in the district 3, is decreasing due to the decreasing trend in population in addition to the efforts of related organizations in expanding the green-space. While, the district 9 having a sharp slope upward in terms of the gap between the desired and the present green-space is worsening. However, in other districts (12, Key words Sustainable development, Per capita green space, desire green space, dynamic system