Abstract: Provided are a waste gas processing device, a vacuum coating system, and an operation method of the waste gas processing device. The waste gas processing device is configured to remove and recover arsenic in the waste gas, and includes a condensation portion and a scraping portion. The condensation portion is provided with a condensation cavity, and an air inlet, an air outlet and a discharge port communicated with the condensation cavity. A partial surface of the scraping portion abutting against an inner wall surface of the condensation cavity. The present disclosure solves a problem in a conventional art that an economic cost of a waste gas processing device is too high during the removal and recovery of arsenic in waste gas.