Bearing the responsibility of the rising strategy of central region of China, Changsha-Zhuzhou-Xiangtan Urban Agglomeration is an important growth pole of the development of the Yangtze river economic belt. Reasonable position of urban function in Changsha-Zhuzhou-Xiangtan Urban Agglomeration, is an inevitable requirement for the cooperative development of regional economy in Changsha, Zhuzhou and Xiangtan. This paper takes the basic economic activities of these cities as the starting point to determine the urban function. Subsequently, this paper uses the related statistical data, introduces multivariate statistical analysis method, such as regression analysis, factor analysis and cluster analysis to clarify the function of 20 cities in Changsha-Zhuzhou-Xiangtan Urban Agglomeration. The findings reveal that the most common functions of the regional urban agglomeration are construction, transportation, postal services, finance, real estate, manufacturing, social services, wholesale and retail industry. At the same time, the paper classifies these 20 cities according to the urban function. The classification results provide the basis for accelerating Changsha-Zhuzhou-Xiangtan Urban Agglomeration construction of urban function.