Abstract: Individually using C16H36O4Ti, CH3COOH, HCl, C9H20O5Si (KH560), C9H14O3Si (Ph-TMS), CH3OH and deionized water as raw material, NH3·H2O as catalyst, anti-photoaging poly (p-phenylene-2,6-benzobisoxazole) (PBO) fibers were prepared by sol-gel method and multiple sol-gel method, respectively. The particle size analyses were done to verify the successful preparation of two kinds of nano-sol. The chemical composition and the physical properties of the surface of PBO fibers were characterized by EDS, SEM, particle size determination and contact angle test to verify the preparation of anti-photoaging PBO fibers. The anti-photoaging property of PBO fibers were characterized by SEM, tensile strength and contact angle test. Results show that after photoaging for 130 h, the tensile strength retention rate of PBO fibers individually coated by nano-TiO2 hydrosol-gel method and nano-organo-silicon sol-gel method are just 5% and 10% higher than the uncoated PBO fiber, respectively. Whereas after aging for 130 h, the tensile strength retention rate of PBO fiber successively coated by nano-TiO2 hydrosol-gel method and nano-organo-silicon sol-gel method is 27% higher than the uncoated PBO fiber, and the surface of the fiber is still complete.