Lead-free　AgNbO3-based　antiferroelectric　(AFE)　ceramics　have　attracted　increasing　interest　owing　to　their　environmentally　friendly　nature　and　excellent　potential　in　energy　storage　devices.　However,　the　poor　breakdown　strength　(BDS)　of　AgNbO3　limits　its　practical　application.　Herein,　the　Mn/Sm-codoing　strategy　and　the　tape-　casting　technique　were　utilized　to　improve　the　BDS　of　AgNbO3-based　ceramics　to　320　kV　cm-　1　,　which　is　almost　1.8　and　1.6　times　greater　than　that　of　doped　AgNbO3　prepared　by　solid-state　reaction　and　that　of　pure　AgNbO3　prepared　by　the　tape-casting　method,　respectively.　The　relatively　high　BDS　is　attributed　to　the　improved　density,　the　grain　size　reduction　and　the　decrease　of　concentration　of　oxygen　vacancies.　As　a　result,　a　high　energy　storage　density　of　5.18　J　cm-　3　with　an　efficiency　of　73.3　%　were　observed.　Our　research　enriches　the　fabrication　strategy　of　lead-free　AFE　ceramics　with　high　BDS　and　contributes　to　the　applications　of　AFE-based　energy　storage　devices.