Abstract: To investigate the evolutionary characteristics of decay phase of the flash temperature produced by hypervelocity impact on dolomite plate, an experimental measurement system platform was established with two-stage light-gas gun loading system and optical pyrometer measurement system, and the hypervelocity impact experiments were executed in two different velocities (as 1.9, 4.2 km/s)at the same impact angle 45. Theoretical and empirical formula was deduced by shock wave theory. The analysis of the results show that the larger the impact velocity is, the longer the decay time will be and that the theoretical derivation formula is better consistent with the experimental data, and it can be used for estimating such collisions radiation decay phase of the flash temperature.