As environmental pollution has become more and more serious, governments of various countries have gradually realized the importance of low-carbon environmental protection and sustainable development. In the process of low-carbon economic development, the evaluation of urban industrial transformation has become the focus of this research. Based on this, in this paper, we have conducted a systematic study on the basic characteristics of low carbon economy and carbon emissions during the evaluation process of low-carbon economy industrial transformation. Based on the investigation of the carbon emission coefficients of different energy sources, an evaluation method using comparative labor productivity and a comparative labor productivity difference index to upgrade the industrial structure was proposed. In addition, a case study was conducted on the economic development and industrial structure of an energy city from 2000 to 2019. Through calculations, in terms of industrial structure, the city's tertiary industry service industry has been vigorously developed, and its proportion has increased from 21% to 36.6%, so its industrial structure and employment structure have gradually become more reasonable. In terms of carbon emissions, the ratio of the tertiary industry's carbon emissions to the total carbon emissions has gradually increased, and the development of the tertiary industry' has received more and more attention. The city's carbon emissions per unit of GDP from 2000 to 2019 have been reduced year by year, from 38,300 tons/billion yuan to 13,000 tons/billion yuan. This proves that the adjustment of the industrial structure of the entire city has promoted the development of low-carbon economy.