The spaceborne hyperspectral imager′s spectral and imaging performance may be altered by the on-orbit vacuum and low-temperature environment. To achieve high-precision quantitative applications, system calibration must be conducted on the ground by simulating the on-orbit environment. This paper takes the advanced hyperspectral imager (AHSI) onboard the GF-5(02) satellite as the research subject and innovatively proposes a synergistic testing method combining thermal focusing adjustment and vacuum calibration, along with constructing a corresponding experimental system. By adopting a thermal focusing strategy of overall temperature variation combined with local fine-tuning, precise calibration of the imager′s focal plane in a vacuum environment was achieved. Subsequently, vacuum spectral calibration was performed, revealing the thermal-optical coupling mechanism responsible for spectral shifts in the shortwave infrared band. The results indicate that the spectral resolution of AHSI is better than 4.83 nm in the visible-near-infrared band and 8.97 nm in the shortwave infrared band. Compared with calibration under normal temperature and pressure, the center wavelength of the shortwave infrared channel exhibited an average shift of 1.83 nm, which is attributed to thermal deformation of the shortwave infrared detection cooling assembly under vacuum and low-temperature conditions. This synergistic calibration system effectively integrates thermal focusing adjustment and vacuum spectral calibration, enabling accurate characterization of spectral and imaging performance under on-orbit working conditions. The system has been successfully applied in the on-orbit detection of methane point source emissions in the Permian Basin in the United States and alteration information of the Liba gold deposit in the West Qinling region of China, demonstrating its high-precision detection capability in ecological environment monitoring and mineral resource exploration. This study provides systematic technical methods, engineering practice references, and a replicable experimental paradigm for pre-launch vacuum calibration of spaceborne hyperspectral instruments, with notable innovations in the thermal focusing strategy for highly integrated optical systems and the analysis of thermal-spectral shift mechanisms.