Multipoint　access　urban　underground　roads　structure　form　complex　and　located　in　the　city　densely　populated　areas.　Pollutants,　such　as　CO　and　NOx,　discharged　by　motor　vehicles　in　the　process　of　running　not　only　threaten　the　health　of　drivers　in　the　tunnel　but　also　affect　the　living　environment　and　health　of　the　people　near　the　tunnel　entrance.　In　this　study,　the　distribution　of　CO　concentration　produced　by　motor　vehicle　emissions　was　investigated　using　the　law　of　conservation　of　mass,　theory　of　parallel　wind　paths,　and　field　measurements　for　four　tunnels　in　Shanghai　and　Changsha.　In　addition,　experiments　were　conducted　using　a　1:8　scale　model.　The　diffusion　characteristics　of　traffic　wind　and　vehicle　emissions　from　multipoint　access　urban　underground　roads　were　studied.　A　prediction　model　for　distribution　characteristics　of　the　CO　concentration　produced　by　vehicles　flowing　in　and　out　of　urban　underground　roads　under　traffic　wind　conditions　was　proposed.　The　proposed　model　included　the　determination　of　key　parameters,　such　as　the　traffic　wind　speed　Vr,　convective　mass　transfer　coefficient　hm,　and　diffusion　characteristic　coefficient　K.　The　measured　results　of　the　Xiangjiang　tunnel　at　Yingpan　Road　in　Changsha　City　verified　the　effectiveness　of　the　proposed　model.　The　error　evaluation　values　Index　of　Agreement　(IA)　of　the　traffic　wind　and　pollutant　concentration　prediction　model　were　0.992　and　0.916,　respectively.　When　the　tunnel　structure　and　traffic　characteristics　are　known,　the　calculation　model　can　be　used　to　predict　and　evaluate　the　average　traffic　wind　speed　and　average　concentration　of　CO　emitted　by　motor　vehicles　in　each　section　along　the　direction　of　motor　vehicles　on　the　multipoint　access　urban　underground　road,　and　to　quantitatively　evaluate　the　influence　of　each　off-ramp　(combined　ramp)　on　the　distribution　characteristics　of　the　CO　concentration　in　the　main　tunnel.　The　obtained　results　can　provide　a　reference　for　scientific　site　selection,　optimized　design　of　ventilation　system,　and　energy-saving　operation　of　multipoint　access　urban　underground　roads.　©　2022,　Editorial　Department　of　China　Journal　of　Highway　and　Transport.　All　right　reserved.