Abstract: Since 2018, the National Natural Science Foundation of China (NSFC) has promoted the systematic reform of science funds. As a reform pilot, the Department of Atmospheric Sciences of the NSFC led the reform of proposal review classification to optimize the layout of discipline funding and formed the 2020 application code configuration through strategic research and discussion. The main structure of atmospheric science contains three categories of sublevel codes: (i) subdisciplines; (ii) supporting technologies; and (iii) development fields, totaling 15 sublevel codes. They also organized experts to systematically sort out and analyze the research directions and keywords of each sublevel code, and after three years of implementation and optimization, they developed the current version. The five research directions and keywords of earth system model development (D0512), a second-level code of the atmospheric science discipline of the National NSFC, are systematically interpreted. This paper introduces the overarching background of D0512’s setup, the overall framework of the research directions and keywords of D0512, and the specific considerations for keywords. The frequency and research hotspots of all the keywords in different directions during the last five years are also analyzed and discussed using the Web of Science database. The existing keywords are found to be reasonable, although there is room for improvement. To enhance visibility and attract more research proposals, the keywords must be constantly modified and updated. There are also suggestions for keyword selection and optimization. It is hoped that the new application code will promote the progress of earth system model development in China.