Abstract: The surface treatment of graphite fibers with Ar,N₂,O₂-plasma was studied.It was found,after the surfase of the graphite fibers was treated with O₂-plasma,the intelaminar shear strength (ILSS) of Graphite Fiber Reinforcecl Plastics (GrFRP) was increased by over 250% and the tensile strength (S) and Young's modulus were increased by 40% and 10%,respectively.It was also found that the relationship between the time of the sutfase treatment of the graphite fiber and the ILSS of the GrFRP was surfase treatemnt of thr graphite fiber and the ILSS of the CrFRP was
ILSS=A+Ce^-B/t.
We found that the shearing fracture of the GtFRP appeared in the surface layer of the graphite fiber.After the graphite fiber surface was treated by O₂-plasma,the resistence of the surface layer to shearing stress was greatly raised by improving the layer structure,which made the ILSS of the GrFRP increased greatly.