Abstract: Based on metal electron gas model, the studies and analysis on the effect of temperature and pressure on gold reflectance characteristics changes were done. The experiments of pressure effect on gold reflectivity characteristics under 488 nm wavelength laser by DAC setup and those of temperature effect under high energy laser which supplies dynamic temperature rise were also done, the reflectance characteristics changes were obtained in 11 GPa pressure range and room temperature to 350 ℃ temperature range. The results show that the pressure effect comparing with temperature effect on reflectivity is negligible, the reflectivity is monotonely increasing and up to 10% increase, there is a one-to-one correspondence between reflectivity and temperature. Through the requirement analysis of temperature measurement in dynamic high pressure condition, the measurement method of material transient temperature can be established by gold reflectivity change under 488 nm wavelength laser in lower temperature (1000 K) section of dynamic high pressure loading.