Abstract: The exploration and evaluation of low-carbon, zero-emission, and maximized coal resource utilization are considered crucial aspects of coal geology in the 21st century. Based on the research content of coal and coal geology and the development trends of clean coal technology at domestic and abroad, this paper defines clean coal geology in both broad and narrow senses, summarizes the composition and distribution of both beneficial and harmful components of coal, and sorts out the geological factors affecting clean coal technology. We also overviews the current state of research on clean evaluation, processing, conversion, and utilization of coal resources. The progress of clean coal geology research in China is reviewed, with the identification of five stages: germination, exploration, maturity, establishment, and expansion. Existing scientific and technical problems such as coal-forming processes, organic-inorganic interactions, mineral matter, and clean efficiency enhancement are highlighted, indicating future developments in chemistry, physics, biology, and big data/artificial intelligence that offer opportunities for expanding clean coal geology and its large-scale engineering applications. The authors suggests a focus on research and emerging achievements in coal and coal-bearing mineral exploration and development, clean processing and utilization, and ecological restoration.