A comprehensive overview of coal oxidation methods under mild conditions is provided, including oxidation with oxygen, ozone, ruthenium ion catalysis, oxidizing acid, electrolysis, sodium hypochlorite, and hydrogen peroxide. The changes in chemical structure of coal during oxidation, the mechanism of different types of oxidation methods, and the possible applications of oxidation products are summarized. Comparison of these oxidation methods demonstrated that hydrogen peroxide and sodium hypochlorite oxidation of coal under mild conditions are the most suitable methods to study the molecular structure of coal and to obtain high-value organic chemicals. Applications of different analytical techniques for determination and quantification of products and coal structures are also reviewed.