A　campaign　of　sampling　atmospheric　precipitation　and　real-time　measurements　of　atmospheric　non-refractory　submicron　particulate　matter　NR-PM1　and　its　component　concentrations　before,　during　and　after　precipitation　at　a　representative　region　in　Beijing　from　December　2016　to　November　2017　was　performed　to　investigate　the　physical　and　chemical　characteristics　of　precipitation,　changes　of　major　ion　components　in　rainwater　during　the　course　of　typical　precipitation　events,　and　impacts　of　typical　precipitation　processes　on　atmospheric　non-refractory　submicron　particulate　matter　NR-PM1　and　its　components.　Backward　trajectory　clustering　analysis　was　deployed　to　study　the　effects　of　air　mass　through　long-range　transport　on　main　ion　components　in　rainwater.　The　results　showed　that　the　precipitation　at　the　representative　region　of　Beijing　in　2017　mainly　occurred　in　summer,　accounting　for　82.2%　of　the　total　rainfall　amount.　The　precipitation　was　mainly　neutral　or　alkaline,　accounting　for　86.7%　of　the　total　precipitation,　and　the　frequency　of　acid　rain　was　very　low.　The　seasonal　variation　of　pH　values　in　the　rainwaters　was　characterized　by　winter＞spring＞summer~autumn.　The　seasonal　variations　of　the　total　ion　concentrations,　total　anion　and　cation　concentrations　in　the　precipitations,　which　in　polluted　days　were　significantly　higher　than　those　in　clean　days,　followed　the　order　of　spring＞summer＞winter＞autumn.　The　annual　average　concentrations　of　water-soluble　ions　in　the　rainwaters　were　characterized　by　NH4+＞Ca2+＞NO3-＞SO42-＞Na+＞Cl-＞Mg2+＞F-＞K+,　among　which　NH4+,　Ca2+,　NO3-　and　SO42-　were　the　most　important　components　in　the　rainwaters,　which　accounted　for　about　more　than　80%　of　the　total　ion　concentration.　The　concentrations　of　all　ions　in　pollution　days　were　higher　than　those　in　clean　days.　During　the　course　of　the　rainfall　with　three　stages　such　as　initial,　middle　and　latter　stage,　the　ion　concentrations　in　the　initial　stage　were　mostly　highest　in　all　stages　of　the　rainwater,　and　were　much　lower　in　the　middle　stage　than　those　in　the　initial　phase,　however,　were　a　little　higher　in　the　latter　stage　than　those　in　the　latter　middle　stage.　The　precipitation　with　smaller　rainfall　and　rainfall　rate　had　stronger　scavenging　effects　on　atmospheric　NR-PM1　and　its　components　in　pollution　days,　while　precipitation　with　larger　rainfall　and　rainfall　rate　showed　weak　scavenging　effects　in　clean　days.　It　is　noted　that　there　were　always　two　important　processes　at　each　stage　of　rainfall,　with　accumulation　of　pollutants　and　formation　of　secondary　pollutants,　as　well　as　the　washout　and　rainout　of　precipitation.　During　this　study,　the　precipitation　in　the　typical　area　was　mainly　affected　by　air　masses　from　the　southeast　of　Beijing,　accounting　for　60%　of　the　total　precipitation,　and　the　southwest,　accounting　for　23%,　which　mainly　occurred　in　summer.　These　air　masses　had　different　effects　on　the　ion　components　in　precipitation.　©　2019,　Editorial　Board　of　China　Environmental　Science.　All　right　reserved.