The research on urban functions can provide important references for evaluating cities and promoting the capabilities of urban impact on their hinterlands. Based on methods such as urban function scale calculation model, Nelson classification, correspondence analysis, urban specialized sectors similarity and B/N ratio,this paper analyses the evolutional characteristics of urban functions in Beijing-Tianjin-Hebei during the period from 2005 to 2015.The results show that: To begin with, the scales of urban industrial function were limited, industrial function of Beijing evolved from sectors of the electronic equipment, petrochemical, steel, automobiles, food and beverage into sectors of automobiles, pharmaceuticals, general equipment, electronic equipment. During the same time, industrial functions were changed in Tianjin from petrochemical, steel, electronic equipment, equipment manufacturing into equipment manufacturing, electronic equipment, new energy vehicles, steel, and for Hebei, it was from steel, equipment manufacturing, petrochemical, food, medicine, building materials, textile and apparel to equipment manufacturing, steel, petrochemical, medicine, building materials, food, textile and apparel. Secondly, the function of the service industry was dominant. This kind of functions in Beijing evolved from sectors including information, business, science and technology, transportation, accommodation and catering, real estate, residential services, culture and sports, to sectors including information, business, science and technology, culture and sports, real estate, finance, transportation, wholesale and retail, accommodation and catering, residential services. In Tianjin, services sectors including transportation, science and technology, commerce and residents' services were replaced by transportation, technology, finance and resident services, while in Hebei, where financial and public service functions were major, the overall change was small. Thirdly, in terms of urban specialized sectors, sectors like mining, construction and other industrial functions got enhanced, and sectors like transportation, information, science and technology, finance and other producer services have increased obviously, and functions about culture and sports have also been upgraded, while sectors like accommodation and catering, real estate functions became weaken, and other sectors remained relatively stable. Fourthly, urban functions in Beijing-Tianjin-Hebei were obviously hierarchical, and cities can be divided into four quite different grades. Beijing was a super large comprehensive service industry city, and Tianjin was a super large major functional city with manufacturing, transportation and residential services. Apart from that, Baoding, Tangshan, Shijiazhuang and Handan were large professional functional cities, and Qinhuangdao, Zhangjiakou, Langfang, Xingtai,Chengde, Cangzhou and Hengshui were small and medium-sized specialized functional cities. Finally, the complementarity of urban functions in Beijing-Tianjin-Hebei was improving, and the scale and scope of the spatial connection of the urban function had enlarged. The development trend of the functional network was based on the core of Beijing, Tianjin and Langfang, while intercity links remained weak among cities in Hebei .