In　order　to　decide　the　construction　scale　of　railways　and　routine　buses,　distribute　the　traffic　volume　reasonably　by　adjusting　the　fare　policy,　the　effects　of　fare　on　traffic　structure　is　studied　in　this　paper.　Questionnaire　investigations　of　public　traffic　mode　split　were　done　in　Beijing.　Influencing　factors　of　selecting　railways　and　buses　are　analyzed.　The　results　show　that　trip　time,　cost,　sex,　age,　occupation,　income,　and　trip　intention　have　marked　influences　on　the　results　of　trip　mode　split.　On　the　basis　of　combination　of　variable　factors,　the　variables　that　should　be　used　in　the　model　were　determined　and　the　model　of　public　traffic　mode　split　based　on　disaggregate　model　is　given　in　this　paper.　The　relationship　between　fare　and　mode　split　is　studied,　which　provided　a　base　for　adjusting　the　structure　of　public　traffic　by　using　the　fare　policy.