The　accidents　in　the　freeway　are　frequent　and　more　serious　on　foggy　days.　Connected　vehicle　(CV)　technology　as　a　new　technology　can　inform　drivers　of　fog　conditions　in　advance　so　the　drivers　can　adjust　their　driving　behaviors　through　Human　Machine　Interface　(HMI)　and　Dynamic　Message　Sign　(DMS)　in　the　fog　warning　system.　The　level　of　driver＇s　compliance　with　a　fog　warning　system　is　the　key　to　assessing　the　effectiveness　of　the　fog　warning　system.　To　evaluate　the　compliance　level　of　fog　warning　system,　the　study　established　a　CV　system　testing　platform　based　on　driving　simulator,　and　analyzed　the　changes　in　driving　behavior　and　influencing　factors　for　drivers　under　three　different　visibility　conditions　(No　fog,　light　fog　and　heavy　fog)　based　on　the　platform,　finally,　comprehensive　evaluation　of　the　optimal　fog　warning　system　under　different　foggy　conditions　based　on　the　compliance　level　were　made.　Research　indicators　are　divided　into　three　aspects:　1)　the　response　degree,　including　the　mean　speed,　the　minimum　speed　in　the　fog　zone,　the　difference　of　the　speeds　when　entering　and　leaving　the　fog　zone,　the　proportion　of　speed　following,　and　the　speed　reduction　proportion　prompt;　2)　the　response　start　time,　which　is　the　time　to　start　slowing　down　to　the　speed　limit;　and　3)　the　response　time　duration,　namely,　the　time　in　which　the　speed　limit　is　followed.　The　results　show　that　the　response　degree　of　the　driver　to　the　fog　warning　system　is　high,　the　fog　warning　system　can　effectively　reduce　the　driving　speed　of　the　drivers　and　improve　the　speed　following　proportion　of　the　drivers,　the　deceleration　ratio　of　the　driver　at　each　warning　point　is　relatively　high,　and　the　influencing　factors　of　various　indicators　are　complex　but　are　mostly　related　to　visibility　and　technical　level.　Comprehensive　evaluation　results　show　that　the　warning　mode　of　the　combined　HMI　and　DMS　has　the　highest　level　of　compliance　under　light　fog　conditions,　and　when　fog　concentration　increases,　compliance　level　of　fog　warning　system　with　HMI　only　is　higher　than　others.　The　study　establishes　a　reference　platform　for　CV　system　and　provides　methods　and　index　system　for　the　compliance　level　of　CV　research.　©　2020　Elsevier　Ltd