Abstract-This paper presents a stable grounding technique for the inner conductor of a coaxial resonator in vacuum and high-power condition applications, where the inner and outer conductors of the coaxial resonator are connected by a flange plate. When this novel technique is applied, the stable and unified microwave grounding ability is increased by making the stress on the contact surface uniform, the reliability of space products is improved by reducing the deformation of the rod-end at a transverse vibration load of 10 g by 75%, and the unstable tiny cracks of the high-power component are fully eliminated.