To　find　the　optimization　setting　methods　of　complex　diagrammatic　guide　signs,　three　types　of　typical　complex　diagrammatic　guide　signs　of　an　urban　expressway　were　chosen,　and　five　setting　methods　(the　status　and　four　types　of　optimization　method)　were　developed　in　this　study　to　conduct　research　on　an　optimization　method　for　complex　diagrammatic　guide　signs.　Based　on　a　driving　simulation　experiment,　nine　evaluation　indexes　were　selected　from　four　levels,　the　running　state,　handling　behavior,　driving　efficiency,　and　subjective　feeling.　The　grey　premium　evaluation　method　was　applied　to　evaluate　the　effectiveness　of　different　setting　methods　of　complex　diagrammatic　guide　signs.　The　results　show　that　the　status　effectiveness　of　three　types　of　diagrammatic　guide　signs　has　not　reached　the　optimal　level,　and　most　of　them　in　the　middle　and　lower　levels　need　to　be　improved.　The　optimal　setting　methods　of　diagrammatic　guide　signs　1,　2,　and　3　are　simplified,　repeated,　and　repeated,　respectively.　The　optimal　setting　methods　of　complex　diagrammatic　guide　signs　can　effectively　improve　the　driving　behaviors.　In　the　four　optimization　methods,　the　influence　of　the　advanced　setting　method　is　more　stable,　which　influences　the　diagrammatic　guide　sign　to　reach　the　general　level　or　higher.　When　the　exit　department　coordinates　with　the　ground　text　setting,　the　guiding　effect　of　three　diagrammatic　guide　signs　lies　at　the　general　level　or　lower,　which　is　barely　satisfactory.　This　research　reveals　that　complex　diagrammatic　guide　signs　with　more　than　two　exits　have　poor　effects　on　driving　behavior.　Related　management　departments　should　strengthen　the　optimization　setting　for　this　type　of　sign.　Different　complex　diagrammatic　guide　signs　have　different　effects　on　driver　cognition　and　behaviors.　To　improve　the　driving　behaviors　effectively　and　guide　the　drivers　to　find　the　destination　exits　quickly,　different　optimization　setting　methods　should　be　carried　out　for　them.　In　practical　traffic　engineering　applications,　the　setting　up　of　complex　diagrammatic　guide　signs　can　be　considered　in　advance　when　the　economic　cost,　spatial　conditions,　and　other　factors　are　limited.　It　is　not　recommended　to　set　the　ground　text　at　the　exit　department.　This　method　does　not　improve　the　driving　behavior　under　the　influence　of　diagrammatic　guide　signs.　©　2018,　Editorial　Department　of　China　Journal　of　Highway　and　Transport.　All　right　reserved.