The invention provides a wet processing apparatus equipped with a built-in gas-liquid separation unit. The apparatus comprises a technological cavity, a gas processing unit and the gas-liquid separation unit which is connected between the technological cavity and the gas processing unit and comprises a conveying pipeline and a filer element. The conveying pipeline comprises an inlet section which is used for conveying a chemical gas-liquid mixture in the technological cavity into the gas-liquid separation unit, a reacting section which is used for placing the filter element and separating the chemical gas-liquid mixture which passes through the filter element to a chemical liquid and waste gas, and a gas exhausting section which is used for exhausting the waste gas to the gas processing unit, wherein the inlet section and the reaction section of the gas-liquid separation unit are located inside the technological cavity.