Herein, the effect of parameters on the longitudinal flexure deformation in laser welding Hastelloy C-276 using the filler wire process is evaluated by combining bending stiffness and load analyses. Results show that the linear heat input and relative wire speed can affect the longitudinal flexure deformation through the bending stiffness and equivalent load. As the linear heat input increases, the equivalent load also gradually increases, and the bending stiffness shows a decreasing→increasing→decreasing trend. Moreover, the equivalent load and bending stiffness will simultaneously increase when the linear heat input increases in a certain range, resulting in a relatively small change in flexure deformation. By increasing the relative wire speed, the bending stiffness of sample is improved, thereby causing a significant reduction in the welding deformation. By selecting small linear heat input and large relative wire speed within reasonable parameters, welding deformation can be restrained.