Abstract: In order to study the secondary oxidation characteristics of soaked coal, 6 kinds of coal samples were used for temperature rising programmed test and specific surface area, pore size and analyzed, the experimental results show that the formation rate and exothermic intensity of secondary oxidation gases of the pre-oxidized soaked coal are higher than that of the pre-oxidized raw coal, and the gas production rate and the heat liberation intensity increase with the increase of the pre-oxidation temperature; the activation energy of soaked coal after pre-oxidation is lower than that of the pre-oxidized raw coal and the un-oxidized coal. With the increase of the pre-oxidation temperature, the activation energy is also reduced, which leads to the increase of spontaneous combustion tendency; the specific surface area of raw coal and soaked coal is decreased with the increase of the pre-oxidation temperature, and the secondary oxidation has little effect on the most probable pore size of the raw coal and soaked coal used in the experiment, which are both about 4 nm. However, the differential pore volume / average pore size of the coal gradually decreases with the increases of pre-oxidation temperature at the same most probable pore size.