As a developed and institutionalized concept, sustainable development has become a comprehensive framework for understanding and analyzing the issues that cities face. As geographical systems, small towns have been created under the influence of space-making factors and forces in a spatial-temporal process, and have always been developed by internal and external process (social, economic, environmental and spatial). As a vital and inseparable ring of settlement at the national, regional and local levels, these towns consist of interrelated components and their sustainable development will result in local and regional sustainable development. Therefore, sustainable development of small towns is an important process and fundamental approach which formed the main framework of the present study. In this regard, physical sustainability concept in the sustainability framework of small towns shows the balance and vibrancy of these small settlements in relation to physical – spatial structures, so that it guarantees the sustainability of settlements in the spatiotemporal trends. So it can be considered a process of development and change, with the aim of improving the quality and quantity of the city's physical structure, among which identifying and strengthening the physical sustainability indicators seeking to improve the physical quality of human settlements and living and working environments of all people, especially poor people, on the way to sustainability is an issue of paramount importance. Therefore, this study is aimed to identify and explain the trend of development changes in physical-infrastructural structure of small towns, and to increase the conceptual-functional importance of physical indicators in small towns of the province. Sustainability Barometer model and radar were used for analyzing the data. The statistical population used in this study consisted of small towns in Mazandaran province. The results show that only the component of functional integration in small towns was in moderate sustainability level, and components of places and facilities qualities were in poor sustainability conditions. Overall, the results indicate that there is weak sustainability in physical dimension of urban sustainable development in small towns.