Abstract: A terahertz wave reflector antenna with a three-meter aperture, comprising a main reflector, a sub-reflector, and a feed source, requires high surface accuracy at the micrometer level. To achieve this, precise measurements of the antenna’s skeleton and reflector are essential. This study proposed a joint measurement technology that combined a laser tracker measurement system with a digital industrial photogrammetry system. The measurement accuracy of this technology was better than 0.351 mm for the spherical nodes of the reflector skeleton. After multiple measurement adjustments, the normal angle deviation of the skeleton’s fine-tuning mechanism was reduced to less than 110.3″, the normal height deviation to less than 5.6 μm, and the surface accuracy of the main reflector achieved 12 μm. The research verifies the feasibility of the proposed measurement technology, establishing a mechanical structure foundation for 500 GHz communications.