It　is　necessary　to　study　the　structural　vibration　induced　by　crowd　excitation　and　the　human　comfort　in　flexible　and　long-span　structures.　Crowd　excitation　is　simulated　by　random　method　according　to　normal　footfall　force　curve　and　other　individual　factors　such　as　distribution　of　crowd,　step　frequency　and　physiological　characteristics.　Different　methods　for　computing　crowd　multiplication　factor　are　compared　and　improvement　advice　is　presented.　A　time-varying　dynamic　crowd　model　which　includes　a　main　uniform　parameters　and　coupling　mass　is　established　according　to　crowd　characteristics.　The　dynamic　coupling　equations　for　structure　and　walking　crowd　are　established　and　the　analytical　expression　is　given.　The　crowd　excitation　is　determined　by　random　simulation　and　coupling　mass　method,　the　dynamic　interaction　between　crowd　and　structure　is　analyzed　and　compared.　The　results　show　that　both　the　methods　presented　in　this　paper　are　comprehensive　and　accurate.