Huayang coal preparation plant of the original slime drying tail gas purification system does not meet the relevant regulatory requirements, can only reduce the hourly processing capacity of drying equipment, affecting normal production. In view of this problem, the tail gas purification system of the coal preparation plant was reformed. After analysis and research, the transformation was carried out by keeping the original dust removal facilities unchanged and adding a wet electrostatic precipitator at the outlet of the spray tower to form a three-stage series dust removal process, that is, the flue gas of the slime drying furnace-cyclone dust collector-spray tower-wet electrostatic precipitator-flue gas cylinder standard direct discharge. Practice shows that after the transformation, the average content of solid particles in the exhaust gas of the drying workshop is reduced to 8.3 mg/m3, which meets the requirements of the pollutant emission limit of solid particles ≤20mg/m3, and the coal slime drying workshop of the coal preparation plant can operate normally all day, with remarkable economic benefits.