In　order　to　research　overtaking　behavior　on　two-lane　highways,　the　returnable　time　headway　and　the　overtakable　time　headway　were　defined　and　their　critical　gap　values　were　attained　according　to　overtaking　experiment.　The　minimum　traffic　capacity　of　one-lane　highway　and　two-lane　highway　were　theoretically　analyzed,　and　the　reason　that　two-lane　highway　traffic　capacity　is　smaller　than　twice　as　that　of　one-lane　was　explained　rationally.　Finally,　the　following　time　headway　and　following　rate　of　two-lane　highways　in　China　were　confirmed.　Results　show　that　according　to　the　field　data　and　fitting　simulation　experiment,　the　basic　traffic　capacity　on　two-lane　highways　is　3000　pcu·h-1.