The　high　voltage　circuit　breaker　plays　an　important　role　in　the　circuit.　In　order　to　extend　the　service　life　of　the　circuit　breaker,　it　is　necessary　to　have　materials　with　excellent　ablation　resistance.　At　present,　The　PTFE　with　boron　nitride　(BN)　is　widely　used　to　produce　the　nozzle　of　high　voltage　circuit　breaker.　With　the　increase　of　BN　filler　particle　size,　the　arc　ablation　performance　of　the　composite　increases　gradually.　In　order　to　obtain　the　nozzle　material　with　excellent　ablation　performances,　nanoscale　and　microscale　h-BN　were　divided　into　five　groups　with　different　mass　ratio,　then　added　into　PTFE　to　prepare　five　kinds　of　composite　materials　with　constant　BN　mass　fraction.　To　study　the　influence　of　mass　ratio　on　the　thermal　conductivity　and　arc　ablation　characteristics　of　PTFE/BN　composites,　arc　ablation,　thermal　conductivity　and　spectral　reflectance　are　tested.　After　adding　microscale　and　nanoscale　hybrid　BN,　the　ablation　amount　of　the　composite　decreased　firstly　and　then　increased,　reaching　the　minimum　in　the　third　group.　This　work　indicates　there　is　a　certain　proportion　with　the　excellent　performance　in　arc　ablation　characteristics.　This　paper　offers　a　feasible　method　for　the　preparation　of　PTFE/BN　high-voltage　circuit　breaker.　©　2020　IEEE.