Abstract Structural materials for satellites call for reliant stiffness while meeting the requirements of strength. Cyanate resins with superior mechanical properties and reliable dimensional stability have come under the light in the aerospace field. Herein, TDE‐86 epoxy resin was adopted to modify bisphenol E cyanate resin to prepare a high‐performance composite matrix with superior mechanical properties, low molding temperature and adequate toughness. The silica‐coated carboxylated multi‐walled carbon nanotubes (SiO 2 @MWCNT) was designed and synthesized by sol‐gel method for the reinforced preparation of high‐modulus cyanate/epoxy composites. The experiment results demonstrated that the mechanical properties of the resin matrix could be effectively enhanced by the introduction of SiO 2 @MWCNT, and the optimal overall performance was achieved with 0.9 wt% SiO 2 @MWCNT. Compared with unmodified resin matrix, the incorporation of SiO 2 @MWCNT contributes a large increase in the storage modulus and glass transition temperature. Benefit from the addition of nanomaterials, the curing temperature and viscosity of cyanate resin modified by epoxy resin were further reduced to nearly 70 °C and 40 mPa ⋅ s, which makes the composite matrix retain excellent processing properties.