Abstract: The word "location" is derived from the German standort. Stand means standing place and ort means location. A core idea of location theory is the "least cost" to get "maximum profit". City is a place for human life and engaged in non-agricultural industries production. Urban location theory refers to considering various regional factors to achieve with the least cost to obtain the maximum profit and the best result when constructing cities, selecting city sites, determine size of cities and so on. Urban location affected by many factors, for example terrain, climate, the river, natural resources distribution, the traffic, etc. And it can be divided into natural geographical location, economic geographic location, political culture geographical location, etc. By analyzing existing literature, it can be founded as follows:(1)Urban location theory research has been from center model which under space equilibrium conditions of a single function to the balanced system of multiple functions.(2)Natural geographical background made the central city location research and regional development closer together. Through field investigation and analysis of the natural geographical conditions and regional factors, Duan Hanming thought that the northwest region of China was faced with fragile ecological environment and unfavorable developments location, both development costs and development difficulty were higher than other provinces. The development of cities in northwest region was the result of many factors work together, such as political, economic, natural conditions, resources, ethnic and cultural and so on. And it should focus on the intersection which a variety of factors coordinate with each other and seek the balance point of their common action to ensure urban development rationality, stability and sustainability. Taking 30 prefecture level cities in northwest China as the research objects, this paper uses location remote degree to measure geographic location, economic relation force model to analyze economic location condition, and the improved location advantage potential model to measure comprehensive location quantitatively. The results show as follows:(1)For the nearby provincial capital cities, 30 cities' remote degree value are less than 1, they are not at a remote location, and for Beijing, the remote degree values of the 30 cities is between 0.263 and 2.446, and there are 12 cities in a remote area. The integrated remote degrees show that, the proportion of the 30 cities which locate in remote, not remote and very not remote region, respectively is 13.33%, 53.33%, 33.33%.(2) Economic links shows the following characteristics, for 30 cities, internal links is much higher than the links of the 30 cities to Beijing and their total contact accounted for 99.47% and 0.53%. Apart from Qinghai Province, the internal contact degree of the other 4 provinces is stronger than the external contact degree. Economic links substantially decreases along the direction from east to west with a province as a unit.(3) The economic location in Shaanxi Province obviously presents annular ring structure with Xi'an and Xianyang City as the center, and economic link force is waning from inside to outside.(4) Combined geographically remote degree, economic location and comprehensive location, it can be divided into 4 types for 30 cities as double superior type, geographical location-lag type, economic location-lag type and double-lag type.

Key words: Northwest Region, urban location, geographical remote degree, economic link force