Composite dielectrics with excellent electrical properties are integral to today's energy industries and power infrastructure. Epoxy resin filled with inorganic nano-fillers has been extensively studied for its excellent performances. In this paper, barium titanate (BaTiO3) nanoparticles are selected as the fillers and fluorinated by plasma treatment. The morphology, element content and chemical bond of BaTiO3 and fluorinated BaTiO3 fillers are characterized by SEM, EDS, XPS and FTIR, respectively. The influence of filler concentration and fluorination on flashover voltage of epoxy resin composites was studied. We found that the fluorinated BTO could improve the compatibility of filler and matrix and surface insulation of epoxy resin composites. Finally, the relationship between filler concentration, dielectric constant, fluorination treatment and charge dissipation was analyzed, and the trap distribution on the surface of composites was calculated by isothermal surface potential decay method. Fluorinated BaTiO3 particles as fillers blended with epoxy resin have great engineering application potential.