Abstract: The proposal of the ‘dual carbon’ goal has initiated extensive and profound changes, and the spatial planning of national land should implement low-carbon development to respond positively. Among it, the urban system as the development framework is an effective starting point for coordinated low-carbon development, while the county urban system as the basic unit can most directly and effectively coordinate low-carbon development. Taking Quanzhou County, Guilin City, Guangxi Zhuang Autonomous Region as an example, this study explores the accounting methods of township carbon emissions and carbon sequestrations, analyzes the characteristics of county carbon emission and carbon sequestration, and then optimizes the county urban system according to the idea of ‘carbon function classification-carbon function positioning-industrial guidance’, so as to promote the implementation of low-carbon development in the spatial planning of national land and help realize the ‘dual carbon’ goal.