The　drastic　changes　of　the　space　environment　at　the　tunnel　entrance　can　lead　to　frequent　accidents　with　higher　levels.　The　connected　vehicle　environment　provides　drivers　with　surrounding　traffic　information　and　improve　their　driving　behavior　by　helping　them　make　safe　decisions　efficiently.　As　such,　this　study　is　to　examine　the　effects　of　the　connected　vehicle　environment　on　driving　behavior　and　safety　at　the　tunnel　entrance　zone.　To　this　end,　this　research　simulates　a　connected　vehicle　environment　and　provides　driving　aids　through　the　Human-Machine　Interface　(HMI).　Secondly,　40　participants　with　diverse　backgrounds　drove　the　simulator　under　two　different　driving　conditions:　HMI-OFF　(traditional　driving　environment)　and　HMI-ON　(connected　vehicle　environment).　Finally,　indicators　are　selected　from　speed　control,　stability　and　urgency　to　analyze　the　impact　of　the　connected　vehicle　environment　on　drivers＇　behaviors　and　safety　at　the　warning　zone　and　tunnel　entrance　zone.　The　results　show　that　in　the　connected　vehicle　environment,　the　drivers＇　speed　control　in　the　warning　zone　is　improved　and　their　deceleration　behavior　is　advanced.　The　driver＇s　speed　control　and　stability　are　improved　while　the　danger　level　of　the　accident　is　reduced　100　m　ahead　of　the　tunnel　entrance.　Besides,　the　driver＇s　speed　control　and　stability　have　been　both　improved　300　m　after　the　tunnel　entrance.　Overall,　in　the　connected　vehicle　environment,　the　driver　can　recognize　the　tunnel　in　advance　and　adjust　his　driving　speed　in　time　to　ensure　his　safety　at　the　tunnel　entrance.　The　results　of　this　study　play　a　critical　role　in　the　design　and　research　of　warning　systems　in　a　connected　vehicle　environment,　and　will　also　guide　vehicle　manufacturers　in　designing　safety-related　functions　of　automated　vehicles.　In　this　research,　a　connected　vehicle　environment　test　platform　based　on　driving　simulation　technology　is　constructed　and　tested　in　specific　tunnel　entrance　scenarios,　which　provides　a　reference　for　realizing　active　protection　of　vehicles　at　the　tunnel　entrance.