The water curtain purifier directly uses the fan exhaust air to fully contact with the water in the tank, forming a circulating water curtain on the flood plate. Spray paint waste gas after being washed by the water curtain along the lower edge of the flood plate skimming over the water into the gas water channel, the waste gas in the gas water channel and water mist intense impact mixed. Part of the lifted water in the air water channel falls back to the tank directly under the action of gravity, and the other part rises with the exhaust air flow, falls back to the overflow tank after the separation of the water baffle plate, and then returns to the tank along the upper flood plate and the lower flood plate. The air purified by the water curtain enters the next level of waste gas treatment equipment or is discharged to the outdoor atmosphere by the fan through the exhaust duct. The addition of special flocculant in the circulating tank can make the washed paint mist particles aggregate into loose slag blocks (paint slag), which are collected by the automatic slag collection device in the tank and taken out regularly.