The　seasonal　variation　of　PM2.5　carbonaceous　aerosol　was　investigated　in　Beijing　and　Tangshan　cities　of　China.　The　characteristics　of　carbonaceous　aerosol　(e.g.,　organic　carbon,　OC　and　elemental　carbon,　EC)　under　different　weather　conditions　and　their　source　apportionment　were　also　examined.　The　annual　average　PM2.5　concentration　in　the　study　area　reached　95.6-197.3　mu　g/m(3),　showing　seasonal　and　spatial　variation.　The　carbonaceous　materials　accounted　for　17.3-21.2%　of　the　PM2.5,　and　they　had　a　much　higher　content　under　haze　weather　condition.　It　was　found　that　the　PM2.5　contained　more　OC　than　EC.　Principal　component　analysis　(PCA)　results　indicated　that　the　carbonaceous　components　came　from　mixed　emission　sources　of　coal　combustion,　vehicle　exhaust,　and　biomass　burning.　In　Beijing,　the　vehicle　emission　made　a　contribution　of　63.0　%　to　the　carbonaceous　components　of　PM2.5　in　summer,　which　is　higher　than　that　in　Tangshan.　While　in　Tangshan,　the　coal　combustion　made　a　contribution　of　30.3　%,　which　is　much　higher　than　that　in　Beijing.