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　for　the　cities　that　advocate　the　public　transit　priority.　This　paper　presents　an　urban　public　transit　network　structure　for　the　grid　transit　network　form.　The　urban　public　transit　network　structure　consists　of　primary　routes,　feeder　routes　and　accessorial　routes,　which　are　comprised　of　different　class　transit　lines,　and　transfer　hubs　are　the　key　nodes　connecting　multi-class　public　transit　lines.　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.　To　a　homogenous　region,　the　recommended　values　of　the　key　design　variables　are　put　forward.　The　result　can　provide　the　foundation　for　routes　planning　and　transfer　hubs　location.　©　2016,　UK　Simulation　Society.　All　rights　reserved.