Scientific and reasonable adjustment of urban administrative division is an effective way to improve national governance capacity and promote local development, and the policy of "withdrawing counties into districts" is an important way of administrative division adjustment in recent years. Chengdu-Chongqing Economic Circle(abbr. CCEC) is positioned as an important economic center with national influence, so it needs to be systematically studied from both theoretical and empirical aspects whether the policy of "withdrawing counties into districts" can become a strong thrust for regional economic development. Based on the panel data of 101 sample counties from 2010 to 2019, using a combination of qualitative and quantitative research methods, this paper explores the impact of policy implementation on the economic development of CCEC through the double difference model from the perspective of the specific counties and the overall economic circle. So that we can comprehensively study and judge the impact of the policy of "withdrawing counties into districts" on economic development, zoning adjustment and industrial structure optimization. The results show that the implementation of the policy of "withdrawing counties into districts" has a significant role in promoting the development of county economies in CCEC, which can accelerate the process of economic development. The implementation effect of the policy of "withdrawing counties into districts" has obvious regional differences, among which the implementation effect of Chongqing is better than that of Sichuan. The promotion effect of policy implementation is short-term, and it needs to go through a certain adaptation period to fully allocate municipal resources to drive the development of county economy. The incentive effect will gradually weaken over time. Further mechanism analysis shows that industrial agglomeration effect plays a significant role in promoting the economic development of policy implementation areas. The implementation of the policy of "withdrawing counties into districts" can promote the economic development of CCEC by the industrial agglomeration effect brought by the expansion the city scale and the agglomeration of a large number of enterprises in the region. Industrial agglomeration effect can reduce transportation costs, improve information exchange and improve the efficiency of division of labor and cooperation, and accelerate the high-quality economic development of CCEC. To optimize and adjust the administrative division of CCEC, we should consider the development conditions of each region and implement the division adjustment policy according to local conditions; coordinate the economic development relationship between the central urban area and the surrounding counties, and timely adjust the functional orientation of the urban area and the development pattern of the county according to the future development plan of the region; improve the economic efficiency of policy implementation, scientifically and reasonably tap the potential of resources, and optimize the connotation of zoning adjustment. Starting from the theoretical hypothesis and through a series of empirical analysis and test, this paper makes an in-depth discussion on the economic effect of the county economic zoning adjustment of the typical inland economic growth pole, which is conducive to expand the research on the impact effect of zoning adjustment, and can provide a certain reference for the optimization of local government administrative zoning.