Abstract: The effect of braze welding on the electromagnetic performance of planar slotted waveguide antennas is studied based on inter-disciplinarity. Firstly, according to thermal elastic-plastic theory and birth-death technique, the impact of three factors including cooling curve, solder and clamping method on the antenna′s residual stress and deformation is simulated. Secondly, on the basis of fields coupled mathematical model between structural displacement field and electromagnetic field, the influence of manufacturing errors from braze welding on the antenna′s electromagnetic performance (gain, side lobes, etc.) is explored. Finally, the theory and method are applied to an airborne planar slotted waveguide antenna, some satisfactory results are obtained.