Abstract: In order to explore the law of adsorption and desorption of gas by long-term immersed air-dried coal, unsoaked raw coal and air-dried coal immersed in water for 15 days, one month, three months and five months were selected as samples, through gas adsorption and desorption experiments and liquid nitrogen adsorption experiments. The variation law of gas adsorption and desorption and the distribution characteristics of pore structure of soaked coal for different periods were studied. The results show that with the increase of immersion time, the cumulative gas adsorption of coal sample decreases at first and then increases, the maximum adsorption capacity of coal sample to gas decreases at first and then increases, while the Langmuir pressure increases at first and then decreases gradually; the initial desorption rate of 15-day immersed air-dried coal is higher than that of other long-term immersed air-dried coal, while the desorption rate of the average pore size of BET of coal sample and the cumulative pore volume of BJH increase gradually, and the BET specific surface area of coal sample decreases first and then increases gradually, at the same time, the proportion of micropore and the surface area of micropore related to adsorption capacity also decreases at first and then increases.