Abstract: To improve the agglomeration of nanoparticles and the insulation performance of composite materials, the fluorination process of nanosilica based on dielectric barrier discharge under low pressure was investigated, and the surface fluorination process of nanosilica and its dominant discharge condition were discussed emphatically. Based on the plasma discharge characteristics and emission spectrum diagnosis, the discharge and distribution characteristics of CF₄/N₂ plasma were analyzed, and the micro-characterization of fluorinated nanosilica was obtained. Finally, the effect of the fluorination technology on the electrical properties of epoxy matrix was analyzed. The experimental results indicate that the plasma of CF₄/N₂ with pressure of 10~13.5 kPa and voltage of 5~7 kV is uniformly distributed in the discharge space; And the lowest electron temperature of the plasma is 0.497 eV, which can break the C—F bond and create conditions for the fluorination of nanosilica surface. After effective fluorination of nanosilica by plasma for 10 min, the content of fluorine reaches 10.05%, and the main existing mode of the fluorine element is CF₂. After plasma fluorination, the agglomeration of nanosilica is effectively improved and the dispersion in epoxy matrix is more uniform. After doping with 5% fluorinated filler, the partial discharge initial voltage of epoxy resin will increase most significantly, which is 17.21% higher than unfluorinated sample with the same doping content. The results verify the feasibility of plasma filler fluorination for treating nanosilica filler and provide a novel research idea for fluorinated modified nano-fillers.