中文摘要：

城市经济功能是城市在一定地域经济中所承担的任务和所起的经济中心作用。以生产性服务业为基础的金融、科学研究、信息传输、计算机服务等行业的发展，引起产业结构升级和城市空间结构的相应变化，由此提升了城市的经济功能。本文基于投入产出和城市流强度模型，利用北京市2005和2010年社会经济、投入产出、市辖区人口等相关数据，从城市对内和对外作用两个层面，分别论证生产性服务业的产业关联、空间集聚、产品输出能力等对经济功能的提升作用，结论如下：①北京生产性服务业推动其他产业发展，与制造业融合发展，提升了制造业综合效益，并优化产业结构；②生产性服务业集聚在中心城区，并呈向近郊区扩散趋势，形成特色产业集群，提升了北京集聚经济效益；③生产性服务业专业化水平和城市流强度最高，构成了对外经济联系的主导产业，提升了城市对外资本、技术和人才输出的能力；④生产性服务业净调出额和净出口额均增加，提升了北京国内和国际的服务产品输出能力，并且在国内市场更具有优势，以向外地输出为主。

英文摘要：

The economic function of a city is to undertake the tasks in the economies of certain geographical ar- eas and to serve as an economic center. Urban economic functions can be divided into internal and external eco- nomic functions. External economic functions are based on leading industries or leading economic sectors, main- ly support goods and services for outside areas, and output capital or technologies, whereas internal economic functions provide basic guarantee for production and living activities of the city. Urban internal economic and external economic functions interact with each other and help each other move forward. With the society enter- ing the information age, the producer services, such as finance, science and technology, computer software and information services, have strongly influenced urban industrial and spatial structures, and greatly promoted ur- ban economic functions. Most of the current researches use theoretical analysis to first study the economic func- tions and then the development of producer services. In this paper, by using social economy, input-output, city population data in 2005 and 2010, based on Input-output model and urban flow model, from two levels of inter- nal and external functions, we analyzed industrial relationships, spatial agglomeration and service products out- put of producer services, which have greatly improved economic functions of Beijing City. The conclusions are as follows： （1） Economic contribution rate of Beijing＇s producer service industry is always rising, driving the de- velopment of other industries, but at the same time its development is limited by those industries. It also pro- motes comprehensive benefits of manufacturing industry. Intermediate demand of manufacturing industries and producer services for information, finance, and commercial services increases, which in turn necessitate the up- grade of industrial structure. （2） Financial services, scientific research, information services and business servic- es present an agglomera