In China, the connection between coal utilization and environmental pollution has been increasingly evident due to the rapid growth in energy consumption. Clean coal technology (CCT) is one of the effective methods to address coal-associated pollution. However, CCT needs the practical and theoretical support of clean coal geology (CCG). In this paper, a new definition of CCG is proposed, based on the definitions of coal, coal geology, and CCT, combined with the development of national CCG. CCG is the discipline comprehensively researching the genesis, nature, distribution, cleaning potential, clean utilization and environmental effects of resources (coal, coal bed methane, and other coal-associated resources) that can be cleaned by CCT. The research content of CCG is discussed from different aspects, such as cleaning potential evaluation, geological guarantee for coal mining, ash yields and sulfur contents, trace elements, pollution caused by coal, and mine reclamation. The progress of CCG in China is also briefly divided into four stages and delineated. Finally, scientific problems in CCG are summarized and an outlook for CCG is given.

Clean utilization of coal depends on the quality of raw coal, which depends on the coal-forming parent materials (petrology and chemical composition of coal), the multiple media of the coal-forming environment, and some epigenetic conditions, such as thermal evolution (coalification), magmatic hydrothermal fluid, groundwater. Based on the research results of predecessors and prediction studies of coal resources since the founding of China, the present status of research on coal petrology, coal quality, coal metamorphism, and coal geochemistry in China is discussed in detail, with emphasis on research progress and the general situation of highly efficient and clean utilization of coal in the technical fields of coking, pyrolysis, combustion, gasification, and liquefaction, and the development prospects of coal petrology and coal quality in China are prospected.