Abstract: Using silicon-containing arylacetylene resin(PSA) and acetylene-terminated polytherimide(PEI) as raw materials, the modified silicon containing arylacetylene resin (PEI-PSA) with an acetylene-terminated polyetherimide and the T300/PEI-PSA carbon fiber reinforced composite were prepared by pre-copolymerization. Effects of solvent, reaction temperature and solution concentration on the pre-copolymerization and the dispersion of PEI in PSA were investigated by Dynamic Mechanical Analysis (DMA) and Energy Dispersive X-ray Spectroscopy (EDS). The optimum conditions of the pre-copolymerization were determined and the uniform PEI-PSA resin was obtained. The structures and properties of PEI, PEI-PSA resin and T300/PEI-PSA composites were characterized by Fourier Transform Infrared (FT-IR) spectra, Hydrogen Nuclear Magnetic Resonance (¹H-NMR), Differential Scanning Calorimetry (DSC), Thermogravimetric (TG) analysis, DMA and EDS. Results showed that when the mass fraction of PEI in PEI-PSA resin was 20%, the flexural strength of the produced PEI-PSA resin casting reached 44.5 MPa and increased by 90.2%, as compared with the PSA resin casting. The flexural strength of the T300/PEI-PSA composite reached 602.7 MPa and increased by 124%, as compared with the T300/PSA composite.