Abstract: Numerical simulation of TIG welding of thin wall aluminum cylinder by thermo-elastic-plasic FEM was conducted. Based on the generation of analy sis model, the values and distribution on the whole cylinder for quasi-steady temperature field and residual stress field were described quantitatively.Experiments were performed to verify the residual stress.It can be drawn that during welding there exits high temperature at the centre of heat source and its vicinity where temperature gradient keeps greater.The longitudinal residual stress in weld seam and its HAZ are tensile, its maximum is in the cross-section at the center of weld length and reached 138 MPa.The maximum compressed transverse residual stress was on the both sides of weld seam.The tensile and compressive region of longitudinal residual stress changed alternately at the circumference of cylinder.The residual stress of the welded Al cylinder has been measured by stress-release method, and excellent agreement between the measured value and calculated value is shown.