Urban　public　transit　consists　of　multiple　transit　modes,　such　as　railway,　BRT　and　bus.　The　integration　of　multi-class　urban　public　transit　lines　is　very　important　to　achieve　a　more　efficient　transit　system.　To　the　grid　road　network,　this　paper　presents　an　urban　public　transport　network　structure　integrating　multi-class　public　transit　lines　and　transfer　hubs.　The　urban　public　transit　network　structure　consists　of　primary　routes,　feeder　routes　and　accessorial　route.　Primary　routes　spacing,　MRT　stops　spacing　and　the　size　of　transfer　hub　service　zone　are　the　key　design　variables.　From　the　points　of　view　of　the　traveler,　operator　and　authority　respectively,　the　optimization　objective　functions　for　the　key　design　variables　are　formulated,　and　the　numerical　analysis　is　carried　out　to　find　the　optimal　solution.　For　the　given　input　parameters　values,　the　recommended　values　of　the　key　design　variables　are　put　forward.　The　results　can　provide　a　reference　for　the　integration　planning　of　multi　modal　transit　lines　for　the　big　city.　©,　2014,　Science　Press.　All　right　reserved.