To　calculate　the　public　transit　accessibility　between　a　specific　area　and　its　surrounding　areas,　and　to　show　the　differences　of　the　public　transit　accessibility　more　intuitive,　a　new　concept　is　raised,　this　is　area　public　transit　accessibility　(APTA).　Using　the　GIS　spatial　analysis,　a　method　is　introduced　to　calculate　the　APTA　based　on　bus　station　and　the　boundary　of　the　bus　routes.　Finally,　a　case　study　of　Beijing　Chaoyang　district　is　conducted.　The　results　show　that　the　APTA　can　give　us　a　clearly　description,　about　the　different　levels　of　the　public　transit　accessibility　between　a　specific　area　and　its　surrounding　areas.　This　provides　quantitative　information　of　public　transit　accessibility　for　location　analysis　and　transit　network　optimizing.　Copyright　©2015　by　Science　Press.