Abstract: The clad pipe has a thin inner layer made of stainless steel and a thick outer layer made of carbon steel,and the outer layer has some restriction on the temperature change surrounding the inner layer when butt-welding the inner layer.With finite element method,the temperature field was computed when butt welding inner layer and the stress field of inner layer was computed after butt welding.The convection,radiation and contact effect between the two layers were considered in the FEM model as well as temperature depended material properties.Internal heat generation loading method was applied to simulate heat source,and model change ability to simulate butt weld.The velocity of inner layer butt weld,the temperature and stress field of the inner layer were discussed.Meanwhile the influence of the properties of material,geometry of the plate and the welding heat input on buckling distortion were analyzed based on the simulations.The results indicate that the geometry of the plate and the welding heat input have more effect on distortion than the properties of material.