The　development　of　power　system　requires　power　capacitors　to　have　higher　energy　density　and　smaller　size,　so　to　improve　the　breakdown　strength　(BDS)　of　polypropylene　film,　which　is　the　dielectric　material　of　capacitors,　has　drawn　much　attention.　Nanocomposite　is　a　promising　way　to　achieve　higher　breakdown　strength,　but　the　poor　compatibility　of　polymer　matrix　and　nanoparticles　has　always　been　a　problem.　In　the　present　study,　we　doped　nano-　ZrO2　into　PP　matrix,　and　together　introduced　maleic　anhydride　grafted　polypropylene　(PP-g-MAH)　into　the　nanocomposite　to　form　ternary　system.　Comparing　with　PP　only　doped　with　nano-ZrO2,　the　ternary　system　sample　showed　better　dispersion　of　nanofillers.　Besides,　PP-g-MAH　could　help　build　stronger　force　between　nanofillers　and　PP　which　was　evidenced　by　the　Fourier　infrared　test　and　differential　scanning　calorimetry　test.　Furthermore,　we　performed　dynamic　mechanical　analysis　test　at　different　frequency　and　calculated　the　activation　energy　of　molecular　segment　motions　of　the　ternary　samples,　which　was　about　10%　higher　than　the　binary　samples.　As　a　result,　the　DC　breakdown　strength　of　ternary　samples　was　about　9%　higher　than　the　sample　only　doped　with　nano-ZrO2,　while　the　highest　value　of　387.7　kV/mm　was　obtained.　©　Springer　Nature　Switzerland　AG　2020.