Abstract: This paper defines the conception of urban niche at the beginning，based on the niche theory. Aand then Taking urban agglomeration in Northern Slope of Tianshan Mountains as a case，the niche breadth model，differentiation index model and overlap index model are used to analyze the urban ecological space，niche structure changes and the interaction relations between each other in the urban agglomeration. The main data used in this paper include demographic data，industry figures and investment data from 1980 to 2010. According to the analysis，the results show as follows：（1） In the Northern Slope of the urban agglomeration，the population niche of Urumqi and Shihezi are higher than other cities，while the economic niche and resource niche of Urumqi and Karamay City are the two front-runners. It indicates that urban ecological niche is uncontinuous. （2） As to economic niche，the niche breadth of city with maximum value is 32 times bigger than the city with the minimum in urban agglomeration in Northern Slope of Tianshan Mountains，which indicates that the difference of niche breadth within the urban agglomeration is huge and the polarization effect of central city is prominent in aspect of economic and social development. （3） The population，economic and resource niche differentiation indices show the downward trend，which indicates that the spatial imbalance of population and economy are improving and the gap between population and economic development is gradually diminishing. It also means that urban agglomeration in the Northern Slope of Tianshan Mountains is gradually transforming from single-center into multi-center urban agglomeration. （4） The city niche overlap indices indicate an increasing trend，which reveals that the convergence of industrial structure is increasing and the homogeneous competition is becoming gradually fierce. According to the characteristics of cities in the Northern Slope of Tianshan Mountain and the requirements of the specialization and cooperation，the idea of dislocation development in allusion to the urban groups is put forward at last.

Key words: urban niche, niche breadth, niche overlap, urban agglomeration in Northern Slope of Tianshan Mountains