In　this　study,　the　Aerosol　Chemical　Speciation　Monitor　(ACSM)　was　used　to　conduct　real-time　and　continuous　comprehensive　observation　of　chemical　components　in　non-refractory　submicron　aerosols　(NR-PM1)　from　October　15　to　November　15,　2016.　In　addition　to　that,　the　evolution　characteristics　of　NR-PM1　chemical　components　were　discussed.　The　potential　source　contribution　function　(PSCF)　method　and　a　meteorology-air　quality　coupling　model　system　(WRF-CAMx)　were　applied　to　identify　the　potential　PM2.5　emission　sources　and　transport　path　in　Beijing,　and　the　vertical　distribution　characteristics　of　PM2.5　net　transport　flux.　The　results　indicate　that　the　monthly　average　mass　concentrations　of　NR-PM1　and　PM2.5　were　(59.16±57.05)　μg•m-3　and　(89.82±66.66)　μg•m-3,　respectively.　On　average,　NR-PM1　accounted　for　(70.31±22.28)%　of　PM2.5.　During　the　whole　study　period,　Org,　NO3-,　SO42-,　NH4+,　and　Chl　represented　(42.75±11.35)%,　(21.27±7.72)%,　(19.11±7.08)%,　(12.19±2.64)%,　and　(4.68±3.24)%　of　NR-PM1,　respectively.　The　diurnal　variation　characteristics　of　different　chemical　components　were　disparate.　The　high　potential　source　areas　were　mainly　located　in　southern　Hebei,　northeastern　Henan,　and　western　Shandong　provinces　during　the　whole　study　period.　During　the　haze　episode,　the　potential　regions　of　higher　contribution　were　concentrated　in　Baoding,　southern　Beijing,　and　Langfang.　The　simulation　results　of　WRF-CAMx　showed　that　the　vertical　distribution　characteristics　of　PM2.5　net　flux　varied　with　different　altitudes.　The　adjacent　cities　mainly　export　PM2.5　to　Beijing,　and　the　PM2.5　net　fluxes　mainly　occurred　at　600-800　m　during　the　whole　study　period.　PM2.5　in　Beijing　from　external　sources　mainly　occurred　in　high　altitudes　during　the　early　stage　of　the　heavy　pollution　episode.　Then　it　turned　to　near-ground　transport　until　November　5,　when　the　pollution　was　the　most　severe.　This　indicated　that　high-altitude　and　near-ground　transport　both　played　an　essential　role　in　the　formation　of　heavy　PM2.5　pollution　in　Beijing　during　the　autumn.　Moreover,　two　important　transport　pathways　were　identified:　the　southwest-northeast　pathway　(Baoding→　Beijing→　Chengde)　and　the　northwest-southeast　pathway　(Zhangjiakou→　Beijing→　Langfang-south→　Tianjin).　©　2019,　Science　Press.　All　right　reserved.