| Based on the basic performance test, i.e., the dynamic shear rheological test (DSR test), the thermogravimetric analysis test (TGA test), and the Fourier transform infrared spectrometer (FTIR test), the deterioration characteristics of hydrophobic nano-silica modified asphalt inchlorine salt F-T cycles were systematically studied. The experimental results show that the incorporation of hydrophobic nano-silica can effectively inhibit the deterioration process of asphalt inchlorine salt F-T cycles. The basic performance test and DSR test indicate that the penetration, softening point and viscosity of hydrophobic nano-silica modified asphalt increases by 17.46%, 5.82%, and 7.76%, respectively, and the rut factor increases by 17% to 54%.Besides, the growth rate of hydrophobic nano-silica modified asphalt is much smaller than that of base asphalt, which indicates that the incorporation of hydrophobic nano-silica could effectively reduce the sensitivity of asphalt to the chlorine salt F-T cycle. The TGA test suggests that hydrophobic nano-silica could improve the thermal stability of asphalt, but the thermal properties of hydrophobic nano-silica modified asphaltis significantly affected by chlorine salt F-T cycles, which may be due to the chemical bond formed between the hydrophobic nano-silica and asphalt is more easily destroyed in chlorine salt F-T cycles. The FTIR test indicates that the chemical reaction of asphalt occurs in chlorine salt F-T cycles, but no new functional groups appear. The free hydrocarbon group (3 676 cm-1) has the mostsignificant change, which could effectively describe the damage process of twoasphalt samplesin chlorine salt F-T cycles. There is no obvious change in the functional groups of hydrophobic nano-silica modified asphalt in chlorine salt F-T cycles, and the distribution is relatively stable, with a high performance stability.