Fractal theory and method is applied to analyze the characteristics of low carbon economy connectivity of Jing-Jin-Ji urban agglomeration. Firstly, a “full carbon emission” accounting model is established to calculate the resource consumption and pollution emissions of a single city in Jing-Jin-Ji urban agglomeration in the process of social and economic development. Secondly, the low carbon economic connectivity gravity model and the fractal dimension measurement model are set up to calculate and evaluate the low carbon economic connectivity which centered on Beijing and Tianjin in 2006–2016. There are three main factors in the connectivity gravity model: the population support, GDP output and the road bear of every unit CO_{2} emission. Furthermore, in order to compare and analyze the difference between the single-point radiation source and the double-point source radiation, the superposition effect of the “Jing-Jin” twin-city radiation is calculated according the principle of source superposition. Thirdly, in order to find out the law of the influence of the spatial distribution of single-point radiation connection intensity on the fractal dimension of the source superposition, the representative years are selected to carry out spatial analysis of low carbon economic connectivity based on the tool of ArcGIS. Finally, Xiong’an New Area is treated as the the third radiation center point to calculate and analyze the three-point source radiation superposition. The fractal dimension calculation and analysis results show that in 2006—2016, the low carbon economic connectivity of the Jing-Jin-Ji urban agglomeration have an inverted U-shaped distribution and the peak appears in 2012, which reflect that Beijing and Tianjin had the best combination of low-carbon economy radiation in the urban agglomeration in 2012. The differences of the fractal dimension of low-carbon economic connectivity are very large between Beijing as the central radiation source and Tianjin as the central radiation source in 2007 and 2014, and the inversion of the fractal dimension appears after the dual source superposition, that is the fractal dimension after superposition is lower than the one with higher radiation capacity in a single source, which means that the twin-city linkage is in low effect. The spatial analysis results of low carbon economic connectivity based on ArcGIS show that in 2012, the results of the “Jing-Jin” twin-city radiation low-carbon economic connectivity source superposition shows a reasonable spatial distribution—gradient order and distinct layers, which is the main reason for the peak value of fractal dimension. When Xiong’an New Area is added as the third central radiation source, the fractal dimension of the low carbon economic connectivity of the Jing-Jin-Ji urban agglomeration can be significantly improved.

%U https://xbna.pku.edu.cn/EN/10.13209/j.0479-8023.2019.052