Abstract: The paper researched the coal slurry settling property in Antaibao coal preparation plant,and the coal slurry treated by combination effect of charge neutralization of coagulator and bridging action of flocculant,when the dosage of the PTDN2109+PTDX1220 is 30 g/t+3g/t,the turbidity of clear liquid reduced to 27.9 NTU,and the flock is stable and fluffy,which condition can meet the requirement of normal production in coal preparation,greatly reduced the agent consumption,increased the coal slurry treating effect.