The effects of moisture content on the combustion characteristics and pore structure change of coal slime are studied in this paper. The effect of moisture content on the bed temperature change, combustion efficiency, and NOx and SO2 emission were obtained in a bench-scale fluidized bed reactor, revealing that the lowest bed temperature decreases with the increase in moisture content, but the effect on the highest bed temperature is not the same. Moreover, with the increase in moisture content, the observed degree of blackening of the flue gas increased, and more CO was produced, which in turn leads to a lower combustion efficiency of the coal slime. However, the presence of moisture plays a positive role in the reduction of NOx and SO2 . With the increase in moisture content, the amount of NOx and SO2 produced tends to decrease. The effect of water on the combustion process of slime is mostly the impact of the severe vaporization process in the early stage to form a large water vapor channel, which is beneficial to the evaporation and loss of water, conducive to the reaction of water and coal combustion products, such as the formation of CO, reduction of NOx , SO2 , etc. The large holes formed by the impact of water vapor decreased with the decrease of moisture content, and the nanoscale pores are mostly caused by the combustion process of volatilization and coke formation after the end of vaporization, and increase with the decrease of moisture content.