By using hot air dehydration and microwave dehydration,the dehydration experiment of Xiaolongtan brown coal investigated the moisture absorption of dried brown coal under the simulative air humidity condition on the Southern part of China.The experimental results showed that the hot air dehydration efficiency depended mainly on drying temperature and time.The dehydration efficiency rose with the increasing of the drying temperature and time.However,when the drying temperature was 160 ℃ or higher and drying time was 25 min,the drying dehydration efficiency was not obviously increased by extending the drying time.In addition,the microwave dehydration efficiency could also be influenced by the effective microwave output power and dehydration time.The influence of brown coal sample size on the hot air dehydration was larger than that of microwave dehydration.The ideal dehydration target of brown coal was about 15%.