Much quantitative research (and some qualitative cases) has been done on the role of small- and medium-sized cities in regional development. The present article is also in this line, but with a slight change in the structure of the breakdown in the approach to the subject and the analysis of the problem, and the multi-faceted analysis of the data using the Fuzzy Inference System. The purpose of this research, with regard to the title, is developmental-applicable and has a descriptive-analytical approach. The FIS application and increasing approach has four stages (in general): its Database and Fuzzification; the rules base; the engine; and the Defuzzification. In the glimpse (Knowledge Base), regional development indicators (10 indicators) and variables (more than 70 variables) in four pillars of regional development (economic, physical, infrastructure and human development) for the small- and middle-sized cities of Kurdistan province (9 cities of the city centers Except for Saravabad) were selected and mapped in 2006 and 2016, and then a detailed analysis of the process was performed on the data. The final result of this paper is that although fluctuations in the development of the inland region of the province have been observed, regional development changes (relying on economic indicators) have been consistent with changes in the urban hierarchy (demographic projections). Thus, with the decline of concentration and concentration in Sanandaj, we see an increase in the role of small- and middle-sized towns in the urban-regional development of the province.