Abstract: Vertical deflection is a core parameter for describing the Earth's shape and gravity field characteristics, holding significant importance in geodesy, geophysics, geological hazard monitoring, and marine sciences. A systematic review of the main methods for measuring vertical deflection is presented, including astronomical geodetic methods, global navigation satellite system (GNSS) leveling gravimetric methods, spherical harmonic solutions of the gravity field, and satellite altimetry inversion. The advantages, disadvantages, and applicability of each method are analyzed. Among these, direct measurement methods, such as astronomical geodesy, integrated GNSS with charge coupled device (CCD) technology, and GNSS measurements, can achieve high-precision vertical deflection measurements due to their real-time data acquisition capabilities, but they are limited by environmental conditions and equipment performance. On the other hand, indirect measurement methods, such as gravimetric methods, spherical harmonic solutions of the gravity field, and satellite altimetry, use existing data for calculations, offering higher computational efficiency, but their accuracy depends on high-precision, high-resolution gravity field models or the quality of input data. In general, astronomical geodetic methods (integrated GNSS with total stations for vertical deflection measurements, and integrated GNSS with CCD for vertical deflection measurements) are the primary approaches for directly measuring high-precision vertical deflections and are suitable for high-precision requirements in static environments. GNSS leveling gravimetric methods have been widely applied in ground measurements and regional mapping, but their application is challenging in complex terrain conditions. Spherical harmonic solutions of the gravity field and satellite altimetry methods, with their broad coverage advantages, play a key role in marine vertical deflection measurement and global gravity field research. However, each method has certain limitations, and the need for all-weather, high-precision, automated vertical deflection measurements remains a pressing challenge. Due to the limitations of existing methods under complex weather conditions and the increasing demand for all-weather, high-precision measurements, the development potential of all-weather vertical deflection measurement methods is emphasized. A novel all-weather vertical deflection measurement method integrating GNSS with three-dimensional laser tracking technology is introduced. Advances in instrumentation and data processing technologies indicate future development trends in vertical deflection measurement, including the miniaturization and commercialization of astronomical geodetic equipment, the application of all-weather measurement methods, and breakthroughs in marine vertical deflection techniques. Through advances in equipment innovation, technological integration, and cross-disciplinary applications, vertical deflection measurement technology is expected to play an increasingly important role in supporting Earth science research and engineering applications.