Abstract: The reflectivity characteristic of 30CrMnSiA steel under continuous-wave laser repeated irradiation is explored, by using the double-beam reflectivity measurement device. The reflectivity under only once laser irradiation is compared with that in the process of laser irradiation, cooling, laser re-irradiation. It is found that the reflectivity under the laser re-irradiation is basically the same with the reflectivity corresponding to the maximum temperature in the process of the first laser irradiation, and begins to change only when the temperature exceeds the maximum temperature, and the variation trend of the reflectivity under the laser re-irradiation is the same with that under only once laser irradiation. It indicates that the reflectivity on the surface is related to the maximum surface temperature. The further study results show that the maximum surface temperature could affect the surface oxide layer and the oxide layer thickness does not change in the cooling and re-irradiation process.