Abstract: The poly (dimethylsilane-m-diacetylenyl phenyl) (PDMP) resin was modified by amino diluent (AD) and ethynyl benzoxazine (EB) resin. The modified blending PDMP-EB-AD resin was prepared according to PDMP∶EB∶AD mass ratio=5∶1∶1. The FTIR, DSC, dielectric analyzer (DEA), TGA were used to analyze the molecular structure, viscosity, curing process and heat resistance of the resin before and after modification. The test results show that —NH₂ and —C≡CH in the AD and EB participate in the PDMP curing process. The curing temperature of the PDMP-EB-AD resin increases and the viscosity decreases. The thermal decomposition temperatures (T_d5) of the PDMP-EB-AD resin at N₂ and air are 539.5℃ and 518.7℃, respectively. The mass retention rates of the PDMP-EB-AD resin at 1 000℃ are 85.1% and 18.1%, respectively. The quartz fiber (QF)/(PDMP-EB-AD) composites were prepared by PDMP-EB-AD resin and QF by impregnation and compression molding methods. The adhesion between resin and fiber and the mechanical properties greatly improve. The flexural strength and interlaminar shear strength (ILSS) of the QF/(PDMP-EB-AD) composites at room temperature are 694.5 MPa and 41.9 MPa, respectively, which are 176.6% and 96.7% higher than the QF/PDMP composite under the same conditions, the flexural strength and ILSS at 250℃ are 319.5 MPa and 20.11 MPa, respectively.