Abstract: The atomic emission spectrum of ricochet debris cloud,which was from aluminum plate subjected to hypervelocity impact by aluminum projectile,was obtained by transient spec-troscopy during hypervelocity impact test.The waveband range of spectrum which achieved in the test was 250~340nm.By analyzing the spectrum,six aluminum spectrum peaks were distin-guished from the emission spectrum and two coupling spectrum peaks were decoupled.With the aluminum spectrum constants and intensity of the six peaks,the ricochet debris cloud tempera-tures were diagnosed separately in different impact condition by using the multiple spectrum peaks method.It was found that the temperature would increase when the projectile diameter in-creased and it would increase with the impact velocity increasing,too.By analyzing the test re-sults of different projectile diameter,it was found that the ricochet debris cloud temperature was acutely sensitive to impact velocity.Based on the data achieved in the test,experiential formula describing relationships among ricochet debris cloud temperature,projectile diameter and impact velocity was obtained.Then the radiation characteristics of ricochet debris cloud were studied, every spectrum peak was integrated and the spectrum in the range of 250~340nm was integrat-ed,too.It was found that the spectrum peaks integral,the waveband integral of 250~340nm and impact kinetic energy behave in a linear fashion.The slopes of the spectrum peaks integral to impact kinetic energy were obtained and it could be considered as the radiation efficiency of every spectrum peak in hypervelocity impact.Finally,taking the experiential formula of ricochet debris cloud temperature into consideration,the relation between atom number in the ground state and impact parameter was deduced.The relations among ionization rate,gasification rate and impact parameters were explored.The conclusions would provide technical support for the further studies of the particular cloud temperature produced by hypervelocity impact and the impact parameters deducibility from impact radiation.