Abstract: Basalt fiber reinforced polymer (BFRP) bars are widely used in marine engineering due to their green nature and corrosion resistance characteristics. However, BFRP bars may swell and crack because of water absorption and alkali corrosion during service, resulting in expansion and damage of resin matrix, and even the debonding between basalt fiber and matrix. Swelled matrix accelerated the invasion of water and corrosive ions, exacerbating the degradation of epoxy matrix. In order to prevent moisture intrusion and extend service life of BFRP bars in marine engineering, a hydrophobic fluorinated nano SiO₂ modified epoxy resin was prepared and coated to BFRP bars. The hydrophobic resin can increase the surface contact angle of BFRP from 63° to 106°. Then the original and modified BFRP bars were immersed into in tap water and seawater at 25℃, 45℃ and 60℃ for durability test to explore their variations of water absorption and tensile properties. The experimental results show that hydrophobic modification of BFRP bars can reduce the water absorption, where the water absorption rate of hydrophobic modified BFRP bars is 40% lower than that of original bars after immersing in water at 45℃ for 60 days. The Arrhenius model has been adopted to predict the long-term performance of BFRP bars. Hydrophobic modified BFRP bars show higher tensile strength retention and longer service life than those of original BFRP. Based on above results, it is found that the hydrophobic fluorinated nano SiO₂ modified epoxy resin can reduce the water absorption, improve the strength retention, and prolong the service life of BFRP bars.