Abstract: In order to study the microstructure and heating characteristics of water-soaked air-dried bituminous coal, the bituminous coal samples from a coal mine in Shaanxi Province were selected. Using low temperature liquid nitrogen adsorption instrument and thermogravimetric analyzer, the specific surface area, pore volume and thermogravimetric and derivative thermogravimetric tests were carried out on the coal samples soaked for 30 days, 60 days and 90 days and raw coal samples after constant temperature drying at 25 ℃ for 72 h. The influence mechanism of long-term soaking and air-drying on the physical characteristics and activation energy of bituminous coal during heating process was explored. The results show that the specific surface area and total pore volume of coal samples change with the increase of soaking time. After soaking for 90 days and drying, the contribution proportion of micropore contrast surface area and total pore volume was the largest, and the contribution proportion was larger than that of other pore sizes. It is speculated that the coal sample soaked in water for 90 days after drying, the faster the coal oxygen reaction rate, the higher the coal spontaneous combustion tendency. In the process of heating up, the characteristic temperature difference and characteristic temperature point change of coal samples at different soaking time are different.