Abstract: Under the background of energy structure transition, the utilization of hydrogen resources in coal has become an important direction to support the development of clean energy due to its resource endowment advantages. However, the exploitation and utilization of coal-based hydrogen resources is constrained by the diversity of hydrogen occurrence modes in coal and its dynamic evolution characteristics during coal metamorphism. Based on this, hydrogen resources in coal were taken as the core research subject. First, the classification criteria of hydrogen-rich coal and hydrogen-poor coal were redefined through literature retrieval and statistical analysis. Subsequently, the occurrence and transformation features of hydrogen resources in coal were discussed. Finally, a forecast analysis of these hydrogen resources application trends was described. Findings reveal that the coal with R_o,max < 1.3%, V_daf > 30% and H_daf > 4% is classified as hydrogen-rich coals, and vice versa for hydrogen-poor coals. Hydrogen-rich coal mainly comprised low-metamorphic-grade lignite and long-flame coals, or special genetic coal with exceptionally high liptinite maceral contents such as cutinite, resinite, and barkinite. Hydrogen-rich coal in China exhibits a distinct regional resource distribution pattern characterized by “abundant reserves in the north and specialized occurrences in the south”. In hydrogen-rich coals, more than 80% of hydrogen exists in the alkane side chains or a small amount of alicyclic structure as —CH₃, —CH₂, and —CH structure, while aromatic hydrogen exists in small-size aromatic structure such as benzene and naphthalene. With the increase of metamorphic grade, hydrogen is gradually removed through different carbon polycondensation and dehydrogenation-deoxygenation reactions, successively in the form of H₂O, liquid hydrocarbon, CH₄, and H₂. Because of the reduction of aliphatic hydrogen structures and the increase of aromatic hydrogen in polycyclic aromatic hydrocarbons, the hydrogen-rich coal gradually transforms to hydrogen-poor coal. Meanwhile, based on the preferential release characteristics of aliphatic hydrogen, hydrogen-rich coal conversion technology will focus on co-production of oil and gas technology and coal gasification for hydrogen technology. In addition, the inherent natural hydrogen in coal with rich porosity provides novel approaches for natural hydrogen reservoir exploration and coalbed hydrogen storage, thereby promoting the transformation of coal from a traditional fuel to an integrated resource for hydrogen production and storage.