Abstract: Three dimensional finite element model with different mesh sizes and element orders was established to investigate the effect of high order elements on the deformation in thermal elastic-plastic finite element analysis. The process of CO₂ gas shielded arc welding was simulated by general finite element software ABAQUS. Several conclusions were drawn after comparing the calculation accuracy and time of temperature field and welding deformation between linear element and quadratic element. The results show that quadratic element could better reflect the deformation characteristics in the welded area,and the calculated results were close to the measured ones. The element order had great influence on the stress strain field,but had little effect on the calculated temperature field.