Basalt fiber（BF） was modified by coupling agent（KH550） and nano-SiO₂， and the effect of BF surface modification on the mechanical properties of basalt fiber reinforced concrete（BFRC） was studied. The results show that after modification with KH550 and nano-SiO₂， the surface of BF forms C—H bonds， and the vibration peak corresponding to Si—O—Si bonds becomes stronger. When the amount of nano-SiO₂ is 3% of the mass of BF， the morphology of BF changes most significantly， and the mechanical strength and crack resistance of modified BFRC are significantly higher than those of ordinary BFRC. Under the bridging effect of KH550， nano-SiO₂ can effectively enhance the bonding strength between fibers and the concrete matrix， thereby improving the mechanical strength and crack resistance of BFRC