The characteristics of flash radiation during hypervelocity impact processes were investigated using a flash radiation test system established on a two-stage light gas gun platform. The study explored how impact velocity, projectile diameter, and target chamber vacuum level affect the frequency and time characteristics of flash radiation. The flash radiation test system was designed to precisely measure the frequency and time domain of the flash radiation emitted during hypervelocity impacts. The system is composed of a two-stage light gas gun capable of achieving high impact velocities, a vacuum chamber to control the environmental pressure, and a high-speed spectrometer to capture the emitted radiation. The experimental setup enabled the systematic variation of impact velocity, projectile diameter, and target chamber vacuum level, allowing for a comprehensive study of their individual and combined effects on flash radiation characteristics. The results indicate that the flash radiation in the frequency domain exhibits a dual-component structure, comprising discrete line spectra with fixed wavelengths and continuous spectra. Higher impact velocities and larger projectile diameters, which increase the initial kinetic energy of the impact, enhance the radiation intensity of the flash. Additionally, higher environmental pressures of target chamber increase the frictional heating between the projectile and the gas, further increasing flash radiation intensity. During the decay phase of the flash, increasing the impact velocity raises the plasma concentration, prolongs the duration of the flash, but accelerates the flash temperature decay. In contrast, the projectile diameter has an insignificant effect on the duration and temperature of the flash. Reducing the environmental pressure of target chamber decreases the attenuation during the flash radiation process and extends the duration of the flash. In conclusion, the study provides a comprehensive understanding of the factors influencing flash radiation during hypervelocity impacts. The findings highlight the importance of impact velocity and projectile diameter in determining the intensity and duration of flash radiation and reveal the significant role of environmental pressure of target chamber in modifying the radiation characteristics. These results offer valuable insights for the design and analysis of hypervelocity impact experiments and contribute to the broader understanding of impact physics.