Abstract: The development of polymer dielectric materials with low dielectric constant, low dielectric loss, temperature resistance and high mechanical strength is of great significance to meet the requirements of high performance dielectric materials in 5G field. The hollow SiO₂ nanoparticles (HS) were modified by 1H, 2H, 2H-perfluorooctyltriethoxysilane (PTES), and two kinds of low dielectric poly (aryl ether nitrile) composites (HS@PTES/PEN-F) were prepared by solution casting and phase conversion methods based on fluorinated poly (aryl ether nitrile) copolymer (PEN-F). The successful synthesis of fluorinated poly (aryl ether nitrile) copolymer was confirmed by FTIR and ¹H NMR; the structure and morphology of PTES modified HS were characterized by FTIR, TGA and XPS. At the same time, the dielectric properties, mechanical strength and thermal stability of the HS@PTES/PEN-F composites were studied. The results show that the HS modified by PTES exhibit good dispersion and interface compa-tibility in the PEN-F matrix resin. In terms of dielectric properties, when the content of modified SiO₂ nanoparticles reaches 7wt%, the dielectric constant and the dielectric loss of the HS@PTES/PEN-F composite film prepared by solution casting method are 2.88 and 0.0198 at 1 kHz; the dielectric constant and dielectric loss of the HS@PTES/PEN-F composite film prepared by phase conversion method are 1.19 and 0.0043, respectively. In the aspect of mechanical properties, taking the phase conversion method as an example, when the content of modified SiO₂ nanoparticles reaches 5wt%, the tensile strength and elasticity modulus increase to 10.34 MPa and 365.32 MPa, respectively. In addition, the glass transition temperature of HS@PTES/PEN-F composite film can reach 160℃, which shows good thermal stability.