As a major part of global development governance, G20 countries ' carbon emissions account for 80 % of global carbon emissions. In order to achieve the "carbon neutrality" goal proposed by the United Nations, it is important to compare and analyze the driving factors of carbon emissions in G20 countries and provide suggestions for their carbon elimination. Based on the carbon emission input-output data of seventeen countries out of G20 in the EORA database, this paper compares the driving factors of carbon emissions between the countries from 1990 to 2016 using the weighted average structural decomposition and K-mean model. This paper focus on four driving factors including carbon emission intensity, final demand structure, export structure and production structure. The carbon emission intensity and final demand structure are the main factors of carbon emission reduction and the other two factors have little effect. In G20 countries, Italy was in the first category because it does best on the final demand structure factor, however Australia is in the last category because it does not make full use of four factors. Therefore, the development of energy-saving technologies and adjustment of demand structure has become an important means for countries to transform and achieve carbon neutrality.