Purpose:　Heavy　fog　results　in　low　visibility,　which　increases　the　probability　and　severity　of　traffic　crashes,　and　fog　warning　system　is　conducive　to　the　reduction　of　crashes　by　conveying　warning　messages　to　drivers.　This　paper　aims　at　exploring　the　effects　of　dynamic　message　sign　(DMS)　of　fog　warning　system　on　driver　performance.　Design/methodology/approach:　First,　a　testing　platform　was　established　based　on　driving　simulator　and　driver　performance　data　under　DMS　were　collected.　The　experiment　route　was　consisted　of　three　different　zones　(i.e.　warning　zone,　transition　zone　and　heavy　fog　zone),　and　mean　speed,　mean　acceleration,　mean　jerk　in　the　whole　zone,　ending　speed　in　the　warning　zone　and　transition　zone,　maximum　deceleration　rate　and　mean　speed　reduction　proportion　in　the　transition　zone　and　heavy　fog　zone　were　selected.　Next,　the　one-way　analysis　of　variance　was　applied　to　test　the　significant　difference　between　the　metrics.　Besides,　drivers’　subjective　perception　was　also　considered.　Findings:　The　results　indicated　that　DMS　is　beneficial　to　reduce　speed　before　drivers　enter　the　heavy　fog　zone.　Besides,　when　drivers　enter　a　heavy　fog　zone,　DMS　can　reduce　the　tension　of　drivers　and　make　drivers　operate　more　smoothly.　Originality/value:　This　paper　provides　a　comprehensive　approach　for　evaluating　the　effectiveness　of　the　warning　system　in　adverse　conditions　based　on　the　driving　simulation　test　platform.　The　method　can　be　extended　to　the　evaluation　of　vehicle-to-infrastructure　technology　in　other　special　scenarios.　©　2021,　Xiaohua　Zhao,　Xuewei　Li,　Yufei　Chen,　Haijian　Li　and　Yang　Ding.