Time-space　consumption　method　is　one　of　the　most　essential　methods　for　calculating　the　capacity.　To　promote　the　accuracy　of　the　calculation　result　and　cope　with　the　defect　of　traditional　method　that　neglects　vehicles＇　operating　heterogeneities　on　different　levels　of　the　road,　a　graded　time-space　consumption　method　was　proposed.　The　space　headway　is　a　key　parameter　that　is　the　basis　for　obtaining　reasonable　results　so　that　the　calibration　method　for　space　headway　is　proposed　incorporated　with　the　efficiency　theory.　The　functional　relationship　between　efficiency　and　space　headway　was　obtained　associated　with　Van　Aerde　traffic　flow　model.　For　road　network　in　Beijing,　based　on　the　proposed　model,　the　space　headways　of　vehicles　operating　on　express　ways,　arterials　and　sub-arterials　were　obtained　and　they　are　27.92,　25.56,　and　21.88　m,　respectively.　Finally,　taking　the　new　planned　Beijing　sub　hub,　core　area　of　Tong　Zhou　district　(155　km2)　as　case　study,　the　total　road　network　capacity　of　arterial　and　sub-arterial　was　calculated　by　using　the　modified　time-space　consumption　method　and　the　result　is　0.56-0.60　million　pcu　times　per　day　according　to　the　data　from　investigation.　©　2019,　Editorial　Department　of　Journal　of　Beijing　University　of　Technology.　All　right　reserved.