Abstract: Coal smoldering widely exists in the process of underground coal fire and underground coal gasification. It is of great significance to understand the coal smoldering characteristics for coal fire prevention and clean coal utilization. Current studies focus on the propagation rate and peak temperature of coal smoldering process, and the temporal-spatial evolution characteristics of chemical reaction during smoldering are not clear. Thus, a small-scale vertical reverse smoldering experiment platform was built, and Changcun bituminous coal was used to carry out reverse smoldering experiments under three different wind speeds. A mathematical smoldering model based on the five-step smoldering reaction （evaporation, pyrolysis and three-step oxidation reaction） was established. The changes of reaction rate, reaction front structure and product component in the reverse coal smoldering process under different wind speed were studied. It is found that the pyrolysis reaction rate is much higher than the oxidation reaction rate （about one to two orders of magnitude） during the reverse coal smoldering process, and the remaining solid after the reaction is mainly α-char produced by pyrolysis. Evaporation, pyrolysis and oxidation reactions occur in sequence as the reverse smoldering propagates, but their reaction front overlaps to some extent in space. The thickness of oxidation front is the largest, and the thickness of evaporation front is the smallest. Due to boundary heat loss, the temperature near the wall is low, and the reaction rate of each smoldering step is slow, which makes the reaction front of each step bend to the wall. With the increase of wind speed, the smoldering reactions are obviously enhanced. The heat production effect caused by the enhancement of oxidation reaction not only helps to accelerate the coal combustion process, but also alleviates the bending of reaction front caused by boundary heat loss.