Abstract: Abstract： Urban specialization includes sectoral specialization and functional specialization. The characteristics of sectoral specialization is based on different industrial sectors，and functional specialization is based on different parts、processes、modules of industrial chain. So， urban specialization will be significantly different when using different division system. Using 283 cities as basic spatial units， based on the national census data in 2000 and 2010， computing urban sectoral specialization index 、functional specialization index and location quotients of different sector and function of different scale-group cities，this paper researched phase changes of urban specialization level and specialized sector or function of different scale-group cities. By the research，the following conclusions can be drawn： Firstly，on the urban sectoral specialization，the level of large-scale city was low and declining；and manufacturing， financial and real estate industry， social services industry were more specialized. The level of small-scale city was high and rising；energy production and mining industry， construction， traffic postal industry sectors were more specialized. Secondly，on the urban functional specialization，the level of large-scale city was high and had continued to be higher；the specialization level of management control， technology research， the public service function showed a rising trend. The level of small-scale city was low and had continued to decline，and more specialized in commercial service and production operation function. Thirdly，it is very important to strengthen research on functional division based on industry chain；and functional division is becoming an important driving force for the development of the city and the region of our country.

摘要： 摘要：城市专业化包括产业专业化和功能专业化，其分工特点分别是在不同产业之间进行，和按产业链的不同环节、工序、模块进行。不同的分工体系势必对城市专业化的刻画产生明显分异。基于2000年五普、2010年六普两次全国人口普查分县数据，利用城市产业专业化指数、城市功能专业化指数、区位商指数研究了中国不同规模的城市的专业化水平以及专业化部门的格局与变化。结果表明：城市产业专业化方面，规模较大的城市产业专业化水平较低且呈下降趋势，更专业化于制造业、金融房地产业、社会服务业等产业部门；规模较小的城市产业专业化较高且呈上升趋势，更专业化于能源生产与采掘业、建筑业、交通邮政业等产业部门。城市功能专业化方面，规模较大的城市功能专业化水平较高并有继续升高的趋势，管理控制、技术研发、公共服务功能的专业化水平呈现出不断升高的趋势；规模较小的城市功能专业化水平较低并呈现继续降低的趋势，更加专业化于商业服务和生产操作功能。

关键词: 关键词：城市, 产业专业化, 功能专业化, 分工, Key words： cities, sectoral specialization, functional specialization, division