This article studies the surface modification of PBO fiber by using the polymer coating method. The
impact of surface coating treatment liquor with different concentration and different impregnation process on interlaminar shear strength of the composite materials is investigated through NOL ring interlamminar shear strength test. The results show that the treatment of surface through coating method can increase composite interlaminar shear strength.When the PBO fiber surface after the treatment of twice impregnation process,the efficiency is most obvious. The interlaminar shear strength up to 61% higher than that of the fiber without surface treatment.