The material used in flame tube in an engine is mainly GH99 superalloy. The traditional welding method is resistance spot welding (RSW). In order to improve welding efficiency, reduce machining procedure and weld defect, comparative study of ring-form and C-form laser welding is carried out. The feasibility of laser welding replacing RSW is revealed from weld appearance, microstructure and mechanical properties. In addition, the residual stress and deformation of local and whole component after welding is analyzed by using finite element method (FEM). The results indicate that good appearances are obtained both using ring-form and C-form welding methods, and their tensile-shear strengths are 15.4% and 22.1% higher than that of RSW, respectively. FEM calculation results show that C-form welding can lead to smaller residual stress and deformation compared to ring-form.