We report the flexible PI/BaTiO3 nanocomposites with high dielectric permittivity. The nanocomposites were successfully fabricated by combining electrospinning and electrospraying techniques, followed by hot-pressing method. Scanning electron microscope (SEM), LCR digital meter, thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and electromechanical testing were used to characterize the structure and properties of the composites. The results show that BaTiO3 nanoparticles can be well dispersed in the polyimide matrix by using the combination technique of electrospinning and electrospraying. The dielectric permittivity of the as-fabricated nanocomposites significantly improved with the increase of BaTiO3 volume fraction. The dielectric permittivity and dielectric loss at 50 vol% BaTiO3 content was respectively 28.93 and 0.0084 at 1 kHz. Meanwhile, the nanocomposites exhibited good thermal and mechanical properties.