Abstract: For the study of carbon nanotubes modified RPC（reactive powder concrete） under the action of Cl^- erosion and freeze-thaw cycles on the mechanical properties of attenuation rule, to better promote the engineering application of RPC, with carbon nanotubes content, freeze-thaw cycles times for the parameter variables, the RPC specimens modified by carbon nanotubes were tested by the interaction of Cl^- erosion and freeze-thaw cycles, the influence of parameter changes on the mechanical properties of modified RPC was analyzed, and the attenuation rule of the mechanical properties of the materials was found. The results showed that under the same number of freeze-thaw cycles, an appropriate amount of carbon nanotubes can effectively improve the mechanical properties of RPC, and the more the number of freeze-thaw cycles, the more obvious the increase of fiber on the mechanical properties of concrete. The attenuation analysis of mechanical properties showed that the mechanical properties of each sample decreased continuously with the increase of the number of freeze-thaw cycles, and the fiber incorporation effectively inhibited the attenuation trend. In the 200 th freeze-thaw cycle, the compressive strength and flexural strength of the experimental group with the fiber content of 0.05 % had the lowest attenuation, which were 5.28% and 7.03%, respectively. However, after 200 cycles of freeze-thaw, the concrete strength attenuation phenomenon appeared to restrain, which was analyzed as the influence of secondary hydration. The life expectancy results under the chlorine-freeze-thaw coupling action showed that the addition of carbon nanotubes can effectively improve the service life of concrete, and the average service life was more than 60 years.