Glare　comes　from　natural　or　artificial　light　that　affects　the　driver＇s　ability　to　identify　obstacles　in　front　of　the　road　and　road　driving　conditions,　which　endangers　the　safety　and　comfort　of　driving　and　causes　traffic　accidents.　At　present,　the　theoretical　basis　of　glare　only　considers　the　interaction　between　glare　sources　and　human　eyes.　The　evaluation　methods　and　prevention　measures　of　glare　mainly　focus　on　disability　glare,　which　cannot　use　to　evaluate　glare　in　road　traffic.　It　should　be　relative　to　road　traffic　scenarios　and　driving　task　requirements.　This　paper　analyzed　the　types　and　characteristics　of　glare　sources　in　road　traffic,　the　characteristics　of　a　standard　target　for　visual　recognition,　and　the　visual　condition　and　driver　demand　in　driving　tasks.　The　mechanism　of　glare　in　road　traffic　was　obtained　by　analyzing　safe　and　comfortable　driving.　The　interaction　among　glare　sources,　standard　target,　and　the　driver　was　studied.　A　subjective　scale　was　proposed　for　the　glare　in　road　traffic.　The　results　can　provide　a　theoretical　basis　for　the　measurement　methods　and　evaluation　of　glare　in　road　traffic　and　anti-glare　in　road　traffic　technology.　©　2022,　John　Wiley　and　Sons　Inc.　All　rights　reserved.