[en] Highlights: • Eliminating doping effect and redistributing electric field results in decreased permittivity and increased tunability. • WIncreasing MgO content, permittivity of composite films decreases and tunability shows a trend of first rise and then fall. • The tunability of composite film with 30 wt% MgO under 32.5 kV/mm can reach to 25.6%, 1.22 times that of pure P(VDF-TrFE). -- Abstract: Ferroelectric-dielectric composite has the potential to combine low dielectric constant of the dielectrics with the high tunability of ferroelectrics. However, one significant drawback of the composites is that the decreased dielectric constant is at the expense of tunability. Here, we eliminate the doping effect through organic-inorganic compositing and redistribute electric field to let the tunability increases while dielectric constant decreases. Poly(vinylidene fluoride-trifluoroethylene) copolymers based ferroelectric-dielectric composite films were prepared through spinning-coating method and the effect of MgO content on the dielectric tunable properties was studied. With increasing MgO content up to 30 wt%, the tunability of composite films increased while the dielectric constant decreased. The tunability of P(VDF-TrFE)-MgO composite films with 30 wt% MgO at 10 kHz under 32.5 kV/mm can reach to 25.6%, 1.22 times that of pure P(VDF-TrFE) (20.9%). This research paves a new pathway to increase the tunability and decrease the dielectric constant of ferroelectric materials simultaneously.