The　travel　time　and　interval　of　vehicles　are　sensitive　in　the　urban　public　transport　system.　Even　though　the　scheduled　frequencies　are　fixed,　actual　frequencies　may　fluctuate　heavily.　Based　on　the　theory　of　reliability　and　the　trip　chain　of　public　transit,　the　paper　researched　the　traveling　time　of　buses　and　the　waiting　time　that　passengers　spend　on　stops　from　the　viewpoint　of　the　passengers.　The　models　of　travel　time　reliability　and　waiting　time　reliability　of　transit　have　been　established.　Finally,　the　time　reliability　of　transit　during　evening　peak　hours　has　been　analyzed　and　calculated　using　data　of　the　Beijing　public　transit　system.　©　ASCE.