A three-dimensional finite element model (FEM) was developed by using ANSYS software to reveal the thermal-mechanical behaviors during the pulsed laser welding (PLW) for the fixture restraint in a Hastelloy C-276 butt-welded joint with 0.5 mm thickness. The welding temperature histories and residual distortions were measured to validate the FEM. Based on the FEM, the effects of the restraint distance on transient stresses and plastic strains, residual stresses and distortions were investigated by changing the fixture restraint conditions. The results show that the simulated temperature histories and residual distortions agree well with the experimental results; the restraint distance has a great influence on the magnitude of transient plastic strains, and then the distribution and the magnitude of residual stresses and distortions are changed. Except for the longitudinal residual tensile stresses, the peak values of the transverse residual tensile stresses and displacements and the magnitudes of the angular distortions decrease as the restraint distance decreases from 20 mm to 4 mm. A relatively smaller restraint distance can be used as a cost-effective method for mitigating the transverse residual tensile stresses and the angular distortions, but has an adverse influence on the longitudinal residual tensile stresses