In　this　study,　combined　with　atmospheric　environment　observation　data,　potential　source　analysis　(PSCF)　and　concentration　weight　trajectory　analysis　(CWT),　as　well　as　transport　matrix　and　transport　flux　calculation　methods　based　on　WRF-CMAQ　model,　were　used　to　analyze　the　characteristics　and　causes　of　air　pollution　in　typical　cities　in　Beijing-Tianjin-Hebei　in　autumn　and　winter　of　2019,　and　to　quantitatively　evaluate　the　characteristics　and　causes　of　air　pollution　in　the　Beijing-Tianjin-Hebei　region　and　surrounding　provinces　between　PM2.5　transmission　contribution.　The　results　show　that　the　Beijing-Tianjin-Hebei　region　is　more　polluted　in　winter　than　in　autumn,　and　PM2.5　concentration　has　a　significant　positive　correlation　with　relative　humidity　and　a　significant　negative　correlation　with　wind　speed　during　heavy　pollution　periods.　The　potential　source　regions　of　Typical　Beijing-Tianjin-Hebei　cities　Beijing,　Tianjin　and　Shijiazhuang　are　mainly　distributed　in　Beijing-Tianjin-Hebei,　Shanxi,　central　Inner　Mongolia　and　Shandong,　which　is　basically　consistent　with　CWT　results.　In　the　Beijing-Tianjin-Hebei　region,　local　emission　contributed　most　to　PM2.5　emissions.　The　local　contribution　of　Beijing,　Tianjin　and　Hebei　ranged　from　54.33%　to　66.01%,　and　the　contribution　of　transmission　from　outside　the　Beijing-Tianjin-Hebei　region　ranged　from　0.11%　to　26.54%.　Transport　flux　results　show　that　PM2.5　transport　in　winter　is　mainly　influenced　by　upper-level　northwest　airflow,　especially　in　clean　weather,　where　high　wind　speed　drives　air　mass　inflow.　In　autumn,　it　is　mainly　affected　by　low　level　southeast　airflow.　The　inflow/outflow　and　vertical　distribution　of　transport　flux　show　a　non-linear　response　relationship　with　pollution　level　and　RH.　The　dominant　wind　direction　changes　lead　to　a　significantly　larger　transport　effect　before　heavy　pollution　than　during　heavy　pollution,　and　a　significantly　smaller　transport　effect　in　high　RH　than　in　low　RH.　©　2022　Chinese　Society　for　Environmental　Sciences.　All　rights　reserved.