The invention discloses a purifying device and a purifying method for paint spraying technology wastewater. The purifying device comprises a paint slag settler, wherein a water outlet of the paint slag settler is connected with a water inlet of a water pump, a water outlet of the water pump is connected with a water inlet of a cooler, a water outlet of the cooler is connected with a water inlet ofa coarse granulator, a water outlet of the coarse granulator is connected with a water inlet of an inclined separator, a first oil collector is arranged at the top of the coarse granulator, and a second oil collector is arranged at the top of the inclined separator. The paint slag settler in the device has a good settling effect on the technology wastewater; furthermore, the paint slag settler isfavorable for converging organic liquid, the settled wastewater can be twice separated and purified by coarse granulation separation and the inclined separator after being cooled, organisms in the wastewater can be effectively removed, and the treated wastewater has higher removing force to the organisms in the wastewater again.