Abstract: Along with the advancement of the global carbon peak and carbon neutral, the national ecological environment management strength unceasingly enhances, the industrial waste liquid and the waste gas discharge standard request is getting higher and higher.Incineration is one of the effective ways to treat waste liquid and waste gas in petrochemical industry.Gas-gas heat exchanger is an important component, which exchanges heat between boiler flue gas and waste gas in maleic anhydride incinerator.It has the characteristics of low pressure, large volume, thin wall thickness and high sealing property.The machining quality of the tube holes on the thin-wall tubesheet is one of the important elements that affect the quality of the seal welding between the tubesheet and the tube.In this thesis, the optimum scheme of machining the tube holes on the thin-wall tubesheet is studied to ensure the seal welding quality between the tubesheet and the tube.