Complex　diagrammatic　guide　signs　(DGSs)　are　widely　used.　To　study　the　influence　of　DGSs　with　different　complexities　on　drivers＇　cognition,　four　types　of　typical　DGSs　on　urban　expressways　in　Beijing,　China,　were　studied　through　a　driving　simulator　experiment.　Three　indicators　related　to　eye　movement　and　three　indicators　related　to　driving　behavior　were　collected　and　analyzed.　The　results　indicated　that　the　complexities　of　DGSs　significantly　increased　the　number　of　fixations,　increased　the　number　of　saccades　and　decreased　the　duration　of　the　first　fixation　on　DGSs.　More　complex　DGSs　result　in　a　greater　difficulty　for　drivers　in　recognizing　the　destination　on　the　DGSs.　The　complexities　of　DGSs　also　had　a　significant　effect　on　driving　behavior,　including　increasing　the　standard　deviation　of　the　average　speed,　increasing　the　driving　distance　during　an　acceleration　change　and　increasing　the　average　deceleration.　When　drivers　observed　a　highly　complex　DGS,　the　vehicle　speed　appeared　to　significantly　fluctuate　and　decrease,　and　drivers　required　a　long　time　to　comprehend　the　DGSs.　Under　the　effect　of　different　complex　DGSs,　indicators　of　the　drivers＇　eye　movement　and　driving　behavior　are　closely　correlated,　and　the　average　relational　degree　is　0.645.　In　particular,　relations　of　the　number　of　saccades　on　DGSs　with　three　indicators　of　driving　behavior　and　of　the　driving　distance　during　an　acceleration　change　with　two　indicators　of　eye　movement　are　closer　than　the　relations　between　other　parameters.　This　study　provides　a　foundation　for　the　influence　of　DGSs　on　drivers＇　brain　cognition　and　the　optimization　of　complex　DGSs,　which　will　be　investigated　in　future　research.