The demand for metallurgical coke for blast furnaces is forcing the coke-making industry to look for new sources of coking coals. Noncoking coals are attractive for use in the coke-making coal blends, because they are cheaper and more available. In this study, a Chinese sub-bituminous coal with noncaking property was hydrothermally treated in order to modify its caking and coking properties to be used in coke-making coal blends as much as possible. The caking and coking properties of the hydrothermally treated coals were characterized by solvent extraction, caking index (G(RI)) measurement, and crucible coking determination. The results show that the solvent extraction yield and G(RI) of the sub-bituminous coal can be greatly increased by hydrothermal treatment at proper conditions and the removal of oxygen functional groups, especially the hydroxyl group, thus dissociating the aggregated structure of coal is responsible for the modification results. Crucible coking determinations suggest that hydrothermal treatment can greatly increase the coke strength and the particle coke strength after reaction toward CO2 and decrease the coke reactivity when the hydrothermally treated coals were used in the coal blends instead of the raw coal. Therefore, hydrothermal treatment is an effective method to modify the caking and coking properties of the sub-bituminous coal.