Surface substrate is a concept proposed by the Ministry of Natural Resources for the first time on January 18, 2020 in the “General Plan for the Construction of Natural Resources investigation and Monitoring system”. On December 22, 2011, the “Surface Substrate Classification Scheme” was issued by the Ministry of Natural Resources again, with being further refined. The concept of surface substrate put forward twice has something in common, that is, they both emphasize the basic materials that nurture and support all kinds of natural resources, such as forests, grasslands, water, wetlands and so on, but there are great differences at the same time, that is, there are some differences in the limitation of spatial scope and the definition of content. The paper will make an in–depth study on the essential connotation of this concept, and re–elaborate and supplement its concept and classification more accurately and perfectly by comparing and discriminating with related concepts such as land, land resources, forest site, weathering crustsoil and soil. Meanwhile, the application and research direction of surface substrate in the future is pointed out.