The “one-city” integration of Changsha-Zhuzhou-Xiangtan, on the basis of Changsha-Zhuzhou-Xiangtan integration, is atheoretical conception and practical attempt to advance with the times, and it is a deep way of resource sharing and talent-sharing in the close contact and coordinated development of Changsha-Zhuzhou-Xiangtan region of Hunan Province. It is also the current and future national plan for the development of urban agglomeration in the Yangtze River Economic Belt in China.The main function of the development strategy of Changsha-Zhuzhou-Xiangtan integration formulated and implemented in the past few decades is to improve the development environment of these three cities. The transformation of Changsha-Zhuzhou-Xiangtan integration into “one-city” integration of Changsha-Zhuzhou-Xiangtan will help promote the effective allocation of resources among the three cities. It is of great significance to build China’s fifth growth pole, promote the implementation of the“Three Highs Four News”strategy and promote the formation of China’s dual-cycle pattern. Specifically, the development strategy of “one-city” integration of Changsha-Zhuzhou-Xiangtan can be promoted in terms of concept renewal, top-level design, infrastructure and industrial development, mechanism construction and so on.