A　visual　numerical　simulation　method　is　developed　to　analyze　the　vibrations　of　framed　arch　bridge　under　multi-vehicle　condition.　The　influence　of　parameters　such　as　the　velocity,　number　of　vehicles　and　distance　between　two　adjacent　vehicles　on　the　peak　value　of　vertical　dynamic　response　of　the　bridge　is　studied.　It　is　found　that　resonance　may　occur　as　a　result　of　the　sum　of　free-vibration-response　components　generated　by　each　successive　load　moving　on　the　bridge.　The　resonance　velocity　and　its　corresponding　peak　values　obtained　by　the　simulator　program　for　an　actual　framed　arch　bridge　provide　an　important　basis　to　restrain　the　vehicle-bridge　vibration.