The invention discloses a metal surface dynamic temperature point measurement system based on reflectivity change and a method. The system comprises a heating light source which is connected with a metal sample. A metal film material is plated on the metal sample. The metal sample is arranged on the path of a heating laser beam emitted from the heating light source. The metal sample is connected with a reflection light intensity change test system which is connected with a photoelectric conversion trigger. The system can acquire the dynamic temperature data of the surface of commonly used metal materials, such as aluminum, copper and the like, wherein the metal materials cannot be welded with a thermocouple due to a high thermal conductivity property. The laser irradiation thermal effect of the metal materials is analyzed and evaluated. A basis is provided for laser parameter optimization in the laser processing processes of laser cutting, laser cleaning and the like. The laser energy utilization efficiency is improved. The processing cost is reduced, and other economic benefits are acquired.