A　comprehensive　observation　was　conducted　to　reveal　the　characteristics　of　submicron　and　fine　aerosols　and　their　chemical　components　in　Beijing　in　autumn.　The　potential　source　contribution　function　(PSCF)　and　concentration　weighted　trajectory　(CWT)　model,　Weather　Research　&　Forecasting　(WRF)　and　Comprehensive　Air　Quality　Model　with　Extension　(CAMx)　were　applied　to　identify　the　impacts　of　emissions　from　surrounding　areas　on　PM2.5　concentrations　in　Beijing　for　different　study　episodes.　These　results　showed　that　the　monthly　average　concentration　of　non-refractory　submicron　aerosols　(NR-PM1　)　was　60.20　+/-　53.48　mu　g/m(3),　with　organics　being　the　major　fraction　(42.33%),　followed　by　NO3-　(22.87%),　SO42-　(18.70%),　NH4+　(12.24%)　and　CI-　(3.86%).　The　PSCF　and　CWT　analysis　indicated　common　high　source　regions　was　located　in　the　western　Shandong,　northern　Henan　and　southern　Hebei,　and　the　distribution　of　the　source　areas　usually　varied　with　species　during　different　episodes.　The　regional　source　apportionment　results　revealed　that　52.36%　of　surface　PM2.5　in　Beijing.　was　contributed　by　surrounding　sources　in　terms　of　monthly　mean　and　the　outside　contribution　increased　to　64.56%　during　the　haze　days,　indicating　the　strong　influence　of　regional　transport　on　Beijing　haze　pollution.　Note　that　the　PM2.5　inflows　for　Beijing　mainly　came　from　Baoding　and　Langfang,　and　outflows　towards　Chengde　and　Zhangjiakou,　identifying　two　key　transport　pathways:　the　southwest-northeast　pathway　and　the　southeast-northwest　pathway.　The　PM2.(5)　inflow　fluxes　from　surroundings　were　much　higher　than　outflows　from　Beijing,　leading　to　the　peaking　PM2.5　pollution,　with　the　highest　concentrations　occurring　from　00:00　to　11:00　LT,　14　October　2016.　Based　on　the　net　PM2.(5)　fluxes　and　their　vertical　distributions,　we　discovered　the　PM　(2.5)　transport　mainly　occurred　at　400-800　m　during　the　entire　episode,　while　at　600-1000　m　for　a　heavy　pollution　episode,　both　followed　by　the　southwest-northeast　pathway.　However,　the　PM2.5　fluxes　were　far　lower　for　a　clean　episode,　and　followed　by　the　northwest-southeast　pathway.