Coal is the ballast and stabilizer for ensuring China′s energy security. With the depletion of high-quality coal resources, the utilization of low-quality coal has gradually taken the lead. Low-rank coal reserves are large and have high moisture content, which reducesits subsequent utilization efficiency. Coal drying can effectively reduce coal moisture, improve coal quality, and promote the clean and efficient utilization of high water content low quality coal. The moisture in coal was summarized and classified according to the location andnature of the storage. The classification of the pore structure and oxygen-containing functional groups in coal and the influence of the drying process on the physicochemical structure of coal were reviewed, and the influence of the physicochemical structure of coal on the removal and reabsorption of moisture was then analyzed. The results show that the moisture in small pores and the moisture bonded in theform of hydrogen bonding are more difficult to remove, and the reduction of pore volume and oxygen-containing functional groups after drying can effectively inhibit the moisture reabsorption, and the ignition point of coal is affected by the type of coal and the moisture content,and the upper limit of the drying temperature should be reasonably controlled to prevent overheating and combustion of the coal during drying. The current application status of evaporation drying and dehydration technology was summarized, including drum drying, low-temperature steam drying, fluidized bed drying, vibration mixed-flow drying, microwave drying and other drying methods, and different drying methods were compared and evaluated, and the research direction of future drying technology was explored. The structure of the hotflue gas drying equipment is simple, the processing capacity is large, but the drying process needs to strictly control the oxygen content,and the safety is relatively low. Microwave drying has the advantages of selective heating and fast drying rate, but it may have thermal runaway in the late stage of drying, and it is mainly in the laboratory/ pilot research stage at present. The drying technology using steam as theheat medium has high safety and no waste water and exhaust gas discharge, with low energy consumption and high safety features, and canbe further researched on steam transient drying technology, to solve the safety and high efficiency dewatering and quality improvementof coal with wide grain size.