The invention discloses a coating material for surface modification of PBO (Poly-p-phenylene Benzobisoxazole) fibers. The coating material is prepared from an ultraviolet absorbent, heptadecafluorodecyl trimethoxysilane, cycloaliphatic epoxy resin, a curing agent and an organic solvent. The invention further provides a method for carrying out surface modification on the PBO fibers and surface modified PBO fibers prepared through the method. Furthermore, the invention further provides an extra-high voltage live working tool soft material which is prepared by braiding and twisting the surface modified PBO fibers. The treated PBO fibers overcome the disadvantage of no ageing resistance, have very good insulating performance and can be widely applied to insulating ropes for extra-high voltage live working.