Abstract: In order to obtain the composites with high dielectric properties, polyvinylidene fluoride (PVDF) was used as matrix, graphene oxide modified by ionic liquid as filler (GO-IL) and GO-IL/PVDF binary dielectric compo-sites with different GO-IL contents were first prepared by solution blending method. And then, hydroxylated barium titanate (BT-OH)-GO-IL/PVDF ternary composites with different proportions were prepared by solution blending. The effects of GO-IL and BT-OH contents on the thermal, mechanical and electrical properties of the compo-sites were investigated by FTIR, FESEM, XRD, tensile, electrical and DSC tests. FTIR test shows that IL is successfully grafted on GO, and the addition of GO-IL promotes β-crystal formation of PVDF. DSC and XRD characterizations further improve that the addition of GO-IL promotes the growth of β-crystal. The crystallinity reaches 35.3% and 36.9% when the fillers are 2wt%GO and 2wt%GO-IL, respectively. Electrical test shows that GO-IL is easier to form local conductive networks in PVDF matrix, promoting the electronic displacement polarization and improving the dielectric constant of the composites. For GO-IL/PVDF composite, when the content of GO-IL filler is 2wt%, the dielectric constant of the composite reaches 24.28, which is 2.6 times of the pure PVDF. However, when the filler content reaches 8wt%, the dielectric constant of the composite reaches 78.46, and the dielectric loss also increases sharply, reaching 2.25. The resistance of the composite is 1-2 orders lower than that of the pure PVDF. When the content of GO-IL is 2wt% and the content of BT-OH filler is 20wt%, the composite shows the best comprehensive properties, the dielectric constant is 40.32 and the dielectric loss is 0.38.