Extended Abstract Introduction Today, the city of Kashan faces major problems of urbanization and instability. These problemsinclude unmeasured urban constructions, fragmentation of urban fabric, traffic, high housing prices, environmental problems, an unfair distribution of facilities and services in the city as well asdisorganization in worn-out urban fabrics. To these problems, one can also add the instability of municipality's revenue sources, uncoordinated urban management, and the disorder of the urban image; in order to provide a model to achieve balance in the spatial system of the city,the recognitionof the roots of the formation and occurrence of such problems in form of processes of instability is necessary. Therefore, the aims of the current study are to provide an optimal solution for overcoming various aspects of instability as well as to achieve balance in city’s spatial system, while analyzing the instability processes of the spatial system of the city of Kashan. Considering the significance of this subject, the present research, thus, tries to answer the following question:  what are the most important processes that shape the instability of the space system of Kashan?   Methodology The deployed method in this research is applied-developmental in terms of its purpose and descriptive and analytical in terms of its procedure. To this end, through the review of texts and sources, a theoretical framework was first developed; afterwards, through a pathological approach, while applyingthe analyses from researcher's previous studies, various dimensions of instability in the spatial system of Kashan were extracted, and a way out of city's instability presented.   Results and discussion The findings of the investigation and analyses of the physical-spatial growth trends of Kashan show that A) Between 1355 and 1390, the gross population density of Kashan has decreased drastically. It has decreased to from 140 people per hectare in 1355 to 29.1 people in 2011. This decrease in density implies the horizontal expansion of the city during this period. b) Examining the physical pattern of Kashan based on urban form measurement models shows that the physical-spatial growth pattern of Kashan is a urban sprawl pattern. The coefficients and values obtained from each of the models strongly confirm this idea. Examining the status of urban districts and regions of Kashan in terms of having integrated indicators of sustainable development through a combined approach of multi-criteria decision-making models such as TOPSIS & DEMATEL, ANP showed that districts do not have the same spatial-spatial balance, and they are stratified into three groups: the privileged, the semi-privileged, and the near-privileged. Also, the distribution of development indicators in Kashan shows a kind of spatial imbalance. According to the number of people living in five areas of the city, the findings of the research has shown that nearly 20% of city's population lives in the privileged areas (4 and 5), 54% of the population in the semi-privileged (2 and 1), and 26% of the population in the near-privileged areas which are poor. At last, due to special natural, economic, and social situation of the city as well as its increasing population and excessive physical development, the overall study of the land use of the city, in terms of predictions and goals of the first detailed plan, has revealed a non-observance of planning and urban design standards and criteria. Therefore, if the past trend is going to be kept with, the urban space will not develop based on the future comprehensive plan of Kashan, and its current problems will be far more.   Conclusion Today, cities are facing major problems of urbanization and instability in different dimensions. The findings of the study has shown that medium-sized citiesare among those urban areas which, due to the influence of national mechanisms, face many problemssuch as the instability of income sources, inequality in the allocation of services and facilities.Furthermore, some regional and local processes also intensified instability in such cities. In this regard, the comparison of research findings with theoretical foundations has illustrated that Kashan, as a medium-sized city, is one of the urban areas which faces major problems of urbanization and instability in diverse dimensions. The most important reasons for such problems can be elaborated at two different levels: macro and micro. At the macro level, the chain urban network process at the national level has caused the city to remain economically, socially, and spatiallyweak. At the micro level, processes such as the pattern of scattered urban growth, unbalanced local-spatial development at the level of districts and regions of the city, and the inefficiency of urban development plans have led to the spatial disorder of the city. Therefore, based on the basic theory of the research, effective steps can include solving social, cultural, and service problems, realizing sustainable security, peace and comfort in the urban environment, strengthening the spirit of citizens’ participation in city affairs, and finally realizing social stability with the goal of social justice, economic stability with the goal of economic survival, and environmental sustainability with the aim of ecological balance in the city within the framework of urban development strategies. Taking these steps can also realize a compact physical-spatial form (expansion of intra-tissue concentration) and can increase the level of stability of development indicators at the level of districts and urban areas of Kashan in accordance with the approach of expansion of social justice and reduction of socio-economic differences within the region. In the end, based on the pathology of the instability processes of city's space system, an optimal model is proposed to put Kashan city back on the path of stability of the space system.   Funding There is no funding support.   Authors’ Contribution All authors contributed equally to the preparation of this manuscript.   Conflict of Interest Authors declared no conflict of interest.   Acknowledgments We are grateful to all the scientific consultants of this paper.