Abstract: An ethynyl phenyl azo novolac resin(EPAN) was prepared by Diazo coupling reaction.The ethynyl-containing phenolic resin was used to modify the silicon-containing arylacetylene resin (PSA) through solution blending. The thermal properties of the modified PSA were studied. The modified PSA-EPAN was used to prepare the carbon fabric prepregs. The T300 carbon fabric (T300CF) reinforced the modified PSA-EPAN composites were thermally press-molded, and the mechanical properties of the composites were further investigated. The results show that the EPAN can be well distributed in the PSA matrix, and the cure temperature of the PSA-EPAN blend resin enhances. With mass fraction of 7% EPAN in the PSA-EPAN blend resin, the residual yield at 800℃ in N₂ of the cured blend resin is more than 90%, and the glass transition temperature of the cured blend resin is more than 500℃. The flexural strength of the cured PSA-EPAN blend resin reaches 40.7 MPa which is more than that of the cured PSA resin and increases by 95.5%. The flexural strength and interlayer shear strength of the T300 carbon fabric reinforced PSA-EPAN blend resin composite can reach 423.5 MPa and 29.5 MPa, increasing by 74% and 65%, respectively.