The　real-time　continuous　measurements　of　non-refractory　submicron　aerosol　(NR-PM1)　species　including　organics　(Org),　sulfate　(SO42-),　nitrate　(NO3-),　ammonium　(NH4+)　and　chloride　(Cl-)　in　winter　from　10　December　2015　to　30　January　2016　in　Beijing　were　performed　with　an　Aerodyne　Aerosol　Chemical　Speciation　Monitor　(ACSM).　The　average　concentration　of　NR-PM,　was　81.24　mu　g　m(-3),　with　the　mean　concentration　in　heavy　haze　days　being　220.00　mu　g　m(-3),　similar　to　3　times　higher　than　that　in　light　haze　days　and　similar　to　15　times　higher　than　that　in　clean　days.　Org　was　the　most　significant　component　of　NR-PM1　species,　accounting　for　53%　of　the　total　NR-PM1　for　the　entire　study.　SO42-　was　also　a　significant　component,　accounting　for　23%　of　the　total　NR-PM1.　However,　NO3-,　NH4+　and　Cl-　composition　together　accounted　for　25%　of　the　total　NR-PM1.　All　NR-PM1　species　presented　remarkably　diurnal　cycles　in　haze　days,　characterized　by　the　highest　concentrations　occurring　at　midnight,　and　the　lowest　concentrations　occurring　at　daytime.　Note　that　the　sulfur　oxidation　ratios　were　higher　than　the　nitrogen　oxidation　ratios　for　the　entire　study,　especially　during　the　haze　periods.　The　formation　of　sulfate　was　mainly　affected　by　relative　humidity　(RH),　while　that　of　nitrate　was　more　associated　with　NH3.　Heterogeneous　oxidation　of　NO(2)on　the　surfaces　of　aerosol　particles　might　be　a　significant　pathway　of　nitrate　formations　during　haze　periods.　NR-PM1　was　mainly　from　secondary　chemical　reactions　contributing　46.1%,　vehicle　emissions　contributing　22.3%,　coal　combustion　contributing　16.1%,　and　biomass　burning　contributing　15.6%　in　clean　days.　However,　compared　to　the　clean-day　source　contributions,　the　haze-day　secondary　source　contribution　to　NR-PM1　increased　to　66.8%,　indicating　that　NR-PM1　in　haze　days　was　dramatically　dominated　by　the　secondary　pollutants.