The chemical industry has a large production scale, many products, and very complex processes, so estimating the greenhouse gas (GHG) it produces is not easy. Few comprehensive assessment models at the national level are studied. Emission sources of most models are not complete, and data are outdated. The paper conducts a comprehensive assessment of GHG emissions in China's chemical industry. The emission sources cover direct and indirect emissions. The chemical industry is divided into three main sub sectors to explore GHG flows. GHG flows are examined through chemical production and consumption, and then the emission reduction potential is predicted based on technological developments. The assessment results show that crude oil and coal are the main sources of direct GHG emissions. The indirect GHG emissions are mainly from North China and Northwest China. GHG emissions in the power grid regions are directly related to the distribution of the chemical industry in China. Coal chemical industry has the most GHG emissions. The analysis of driving factors shows that the output effect is the main factor of GHG emissions. Scenario analysis shows that the baseline scenario will reach 6195.95 Mt in 2030. Under the technological improvement scenarios, 589.01 Mt emission reduction can be achieved by 2030 compared with the baseline scenario. Based on the results of the study, this paper provides some policy recommendations.