Abstract: For attaining a better coal slurry water treatment result, comparative test is conducted by Huoshaopu Coal Preparation Plant on the effects that can be obtained with the respective use of the coagulant(dimenthyldiallylammonium chloride) and the flocculating agent alluminium sulfate originally used, through bench-scale comparative test and industrial test. Test results show that the use of the former agent offers a series of advantages over the latter, such as higher treating capacity, lower moisture of filter cake, clearer circulating water, lower energy consumption and lower unit consumption of agent; the cost incurred for treating per ton of slime can be reduced by 2.77 yuan for less dosage of the agent is required(only 8.3 percent of the formerly used flocculating agent); moreover its use can lead to reduction of operating cost and ease of labor intensity, and is in keeping with the aspirations nowadays for building a green coal industry.