Highway　landscape　can　mitigate　the　tiredness　of　drivers,　decrease　accidents　and　increase　the　comfort　of　passengers.　Alignment　is　the　framework　of　highway　landscape.　And　the　minimum　line　length　between　curves　of　identical　direction　based　on　highway　landscape　is　a　index　of　worth　to　be　discussed.　Rendering-observing　experiment　was　done　in　the　research.　This　paper　brought　forward　minimum　line　length　between　curves　of　identical　direction　based　on　highway　landscape　based　on　landscape　design　and　confirmed　the　length　preliminary,　which　make　great　sense　for　the　highway　alignment　design.