Abstract: According to the niche theory and urban niche,the comprehensive level of urban development is measured , the utilization efficiency of urban resources is measured by niche width, and the industrial similarity between cities is measured by niche overlap index. Taking three cities in southern Shaanxi（Hanzhong, Ankang and Shangluo） as the empirical objects, this study put forward the evaluation model of urban comprehensive development, calculated the niche, niche width and niche overlap index of the three cities from the perspective of niche, analyzed the competition and cooperation relationship of the three cities in southern Shaanxi. The results show that Hanzhong city is the core city of the development of southern Shaanxi urban agglomeration, the resource utilization rate of the three cities in southern Shaanxi has been gradually improved in recent years, and the industrial structure of the three cities in southern Shaanxi is highly similar, which leads to more competition among urban development. It put forward suggestions for the development of urban agglomeration in southern Shaanxi, so as to provide some theoretical reference for the overall development of the three cities in southern Shaanxi.

Key words: urban ecological niche, niche width, niche overlap index model, three cities in southern Shaanxi