Abstract: A novel dicyanide-containing silane coupling agent (DCA) was synthesized and characterized with FTIR, ¹H-NMR and ¹³C-NMR. After modified by the coupling agent DCA(2.0wt%), the interlaminar shear strength (ILSS) and flexural strength of the quartz fiber/poly(silicon-containing arylacetylene) (QF/PSA) composites increase by 63.3% and 28.1% at room temperature respectively. The retention of ILSS and flexural strength of QF/PSA are 83.0% and 81.9% respectively at 250℃, the retention of ILSS and flexural strength are 54.7% and 60.0% respectively at 500℃. The decomposition temperature of 5% loss (T_d5) of the cured DCA is 357.8℃, and its residue rate is up to 55.7% at 900℃. According to DSC analysis, the dicyanide groups cure at about 229℃, and the alkenyl groups copolymerized with PSA at 245℃.The strong interfacial layer form between QF and PSA. XPS analysis shows that DCA could form chemical bonds as the bridges between the matrix and fibers. Confirmed by SEM, the rupture mode of QF/PSA composites modified by DCA on the interface is obviously ductile fracture. DCA can apparently modify the interface of QF/PSA composites and improve its mechanical properties.