A　large　luminance　difference　between　outside　and　inside　the　entrance　of　a　tunnel,　with　inappropriate　lighting,　could　result　in　short-term　visual　impairment　and　other　hidden　dangers.　At　present,　almost　all　countries　use　one　luminance　reduction　coefficient　index　to　evaluate　the　daytime　lighting　at　the　tunnel　entrance,　and　their　standard　values　vary.　Studies　have　shown　that　light　sources　have　three　important　characteristics:　color　temperature,　color　rendering,　and　luminous　intensity,　which　all　play　significant　roles　in　driving　recognition　efficiency.　Based　on　the　analysis　of　driving　recognition　safety,　this　article　determines　the　mathematical　relationship　between　recognition　distance　and　luminance　reduction　coefficient　under　different　color　temperatures　using　experimental　data　from　real　vehicles,　and　studies　the　difference　in　recognition　demand　under　different　color　temperatures.　The　gray　target　recognition　experiment　involved　12　drivers　in　36　light　environments　combined　with　different　color　temperatures,　luminance　levels,　and　color　rendering　index　of　70　at　the　tunnel　entrance,　with　good　alignment　elements　and　sight　distance　at　the　speed　of　80　km/h.　The　results　indicate　that　recognition　demands　are　different　under　different　color　temperature　conditions　and　it　is　more　efficient　to　use　both　luminance　reduction　coefficient　and　color　temperature　than　only　luminance　index　in　the　appraisal　of　daytime　tunnel　entrance　lighting.