The appeal of the elements and the regulation of market economy. Once a certain industry and related industries cluster in one place, the technology and the role of monetary externalities will attract more manufacturers into this place, to join the industry, on the one hand, contributed to the formation and development of industrial cluster, on the other hand also provides a foundation for the formation and development of city and carrier. Vendor geographically concentrated and will produce more technology and monetary externalities, so as to further promote the manufacturer lower production costs, increase production efficiency, improve the competitiveness of industrial cluster. The improvement of the economic interests of the industry and improve the economic benefits of the city, many cities it is an important cause of long long. In addition, when the industry cluster development to a certain extent, because many enterprises in the cluster, the market competition is intense, resulting in the external lowers the cluster enterprise's interests. These technologies and monetary externalities, is not only the causes of industrial cluster, and is also the source of the "crowding effect" of industrial cluster, in order to impel the production elements of the cluster and industry to new regional gradient. Industry gradient goes to in different economy.

The level of cities are factors of production and different economic levels of the industry, make urban development in different dynamic of economy of scale, and objectively promoted the development in different economic level of the city, so as to effectively promote the urbanization process.

三、Based on the externality of industrial cluster and urbanization interaction analysis

(a)For urban agglomeration industry cluster of factors of production and industry. City is the factors of production and all kinds of scale of economic activity in the geographical concentration of product. In economics, the urbanization is considered to be a variety of economic elements for the development of non-agricultural industry to the process of urban agglomeration. It includes not only the rural labor force to cities transfer of the second industry and the tertiary industry, including non-agricultural industry investment and technology, production capacity in urban agglomeration. The population of the essence of which is caused by the change of productivity and other economic elements of the process of transformation from countryside to city. So, the elements (mainly labor, namely population) and industry are the two main aspects of urbanization, industrial cluster and urbanization provides the elements for the city and industry agglomeration force and bearing capacity. Under the action of externality, companies within the industry cluster has a higher return on comparative advantage and factor. High returns attract elements flow and concentration to industrial cluster region. For companies at the same time, the effect of the external, enterprises can share the proprietary Labour market of industrial cluster and professional intermediate inputs, and the technology spillover,namely the industrial cluster external economy benefit, the existence of economic interests and produce, attract a large number of enterprises to enter directly, even prompted related businesses. A large number of enterprises to enter and eventually lead to more powerful external economic effect, thus to the enterprise, the factors of production have more appeal, and eventually lead to the formation of industry agglomeration. That is to say, the process of industrial cluster, is also the formation factors of agglomeration and industrial process, is also a factor in the process of urban agglomeration, the rural population into the process of urban population, non-agricultural industries in the process of occurrence and development of the city. As a powerful carrier of the city's economic development, industrial cluster has become the development of city economy of nuclear power. It can provide a lot of jobs for society, attracting a large number of rural labor force to cities, the urban population increase, also drives the city traffic, hotels, conference and exhibition, business and other tertiary industry and the development of the tourism industry, the proportion of the society in the urban economic output rising, regional urbanization process to speed up.