In order to investigate the flash radiation characteristics of different metal targets during high-speed collision, the method of combining the intrinsic and measured spectra is proposed, and a transient spectral detection system is constructed, which is applicable to the complex test environment in the external field. Using this test system, the flash radiation characteristics of steel projectiles colliding with different metal targets (titanium, aluminium and steel) at a speed of 1 300～1 500 m/s were successfully detected, with a wavelength detection range of 350～900 nm. The experiment found that: compared with the three metal targets, the aluminium alloy target is more easily excited and produces the most abundant radiation signature spectral lines, while the special steel target is not found to be obvious strong radiation characteristic spectral lines; in the process of impacting the titanium alloy target and the aluminium alloy target, both of them are found to have the strong radiation characteristic of the obvious Na、K elemental spectral lines; the spectral curves of the same target are in high degree of consistency, which proves that the experimental data can be reproduced.