The present work is aimed at the investigation of a mild, rapid, effective, and recycling desulfurization method of NaBH4 reduction for coal water slurry (CWS). Processing parameters such as reductant concentration of NaBH4, treatment time, particle size of coal, reaction temperature, shaking rate, and initial pH were taken into consideration. The optimum running parameters have been determined as follows: 2.0 mM (0.8 g/L) NaBH4 concentration, 140 mesh coal particle size, 10 min total treatment time, 100 rpm shaking rate, and 30 C reaction temperature. The total sulfur reduction of CWS can reach about 43% operating at the above parameters. Moreover, sulfate sulfur reduction can reach about 47.8%, 55.4% pyritic sulfur can be removed, and 23.9% organic sulfur could be removed. The sulfur content of CWS was decreased by the treatment, and combustion performance was improved. The proposed experimental method for desulfurization of coal in CWS can be used as an alternative to the traditional method.