Abstract: Effect of laser incident angle on welding of Ir-Rh and Ni-based alloy was studied. Optical microscopy, scanning electron microscopy, and energy-dispersive spectroscopy were conducted to analyze microstructure, bonding mechanism of the weld as well as thermal fatigue. The weld mainly consisted of the Ir-Ni solid solution. Thermal fatigue experiment results indicated that the thermal fatigue resistance was affected by thermal stress and high-temperature oxidation. When the laser incidence angle was 10°, the break force of welded joint reached the maximum 163. 3 N, and the best thermal fatigue resistance was obtained. However, the fracture position was less affected by the laser incident angle, and all fracture occurred on the interface between the Ir-Rh alloy and the weld, and the fracture form was mainly intergranular fracture.